diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index c93f2a81c5e..649d1bf812a 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -646,19 +646,26 @@ function request_uri() {
  * @param $type
  *   The category to which this message belongs.
  * @param $message
- *   The message to store in the log.
+ *   The message to store in the log. See t() for documentation
+ *   on how $message and $variables interact. Keep $message
+ *   translateable by not concatenating dynamic values into it!
+ * @param $variables
+ *   Array of variables to replace in the message on display or
+ *   NULL if message is already translated or not possible to
+ *   translate.
  * @param $severity
  *   The severity of the message, as per RFC 3164
  * @param $link
  *   A link to associate with the message.
  */
-function watchdog($type, $message, $severity = WATCHDOG_NOTICE, $link = NULL) {
+function watchdog($type, $message, $variables = array(), $severity = WATCHDOG_NOTICE, $link = NULL) {
   global $user, $base_root;
 
   // Prepare the fields to be logged
   $log_message = array(
     'type'        => $type,
     'message'     => $message,
+    'variables'   => $variables,
     'severity'    => $severity,
     'link'        => $link,
     'user'        => $user,
diff --git a/includes/common.inc b/includes/common.inc
index 1da21609595..d59e864a94f 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -332,7 +332,7 @@ function drupal_site_offline() {
 function drupal_not_found() {
   drupal_set_header('HTTP/1.1 404 Not Found');
 
-  watchdog('page not found', check_plain($_GET['q']), WATCHDOG_WARNING);
+  watchdog('page not found', check_plain($_GET['q']), NULL, WATCHDOG_WARNING);
 
   // Keep old path for reference
   if (!isset($_REQUEST['destination'])) {
@@ -362,7 +362,7 @@ function drupal_not_found() {
  */
 function drupal_access_denied() {
   drupal_set_header('HTTP/1.1 403 Forbidden');
-  watchdog('access denied', check_plain($_GET['q']), WATCHDOG_WARNING);
+  watchdog('access denied', check_plain($_GET['q']), NULL, WATCHDOG_WARNING);
 
 // Keep old path for reference
   if (!isset($_REQUEST['destination'])) {
@@ -556,7 +556,7 @@ function drupal_error_handler($errno, $message, $filename, $line) {
       drupal_set_message($entry, 'error');
     }
 
-    watchdog('php', t('%message in %file on line %line.', array('%error' => $types[$errno], '%message' => $message, '%file' => $filename, '%line' => $line)), WATCHDOG_ERROR);
+    watchdog('php', '%message in %file on line %line.', array('%error' => $types[$errno], '%message' => $message, '%file' => $filename, '%line' => $line), WATCHDOG_ERROR);
   }
 }
 
@@ -653,7 +653,7 @@ function fix_gpc_magic() {
  * - %variable, which indicates that the string should be highlighted with
  *   theme_placeholder() which shows up by default as <em>emphasized</em>.
  *   @code
- *     watchdog('mail', t('%name-from sent %name-to an e-mail.', array('%name-from' => $user->name, '%name-to' => $account->name)));
+ *     $message = t('%name-from sent %name-to an e-mail.', array('%name-from' => $user->name, '%name-to' => $account->name));
  *   @endcode
  *
  * When using t(), try to put entire sentences and strings in one t() call.
@@ -2041,14 +2041,14 @@ function drupal_cron_run() {
     if (time() - $semaphore > 3600) {
       // Either cron has been running for more than an hour or the semaphore
       // was not reset due to a database error.
-      watchdog('cron', t('Cron has been running for more than an hour and is most likely stuck.'), WATCHDOG_ERROR);
+      watchdog('cron', 'Cron has been running for more than an hour and is most likely stuck.', array(), WATCHDOG_ERROR);
 
       // Release cron semaphore
       variable_del('cron_semaphore');
     }
     else {
       // Cron is still running normally.
-      watchdog('cron', t('Attempting to re-run cron while it is already running.'), WATCHDOG_WARNING);
+      watchdog('cron', 'Attempting to re-run cron while it is already running.', array(), WATCHDOG_WARNING);
     }
   }
   else {
@@ -2063,7 +2063,7 @@ function drupal_cron_run() {
 
     // Record cron time
     variable_set('cron_last', time());
-    watchdog('cron', t('Cron run completed.'), WATCHDOG_NOTICE);
+    watchdog('cron', 'Cron run completed.', array(), WATCHDOG_NOTICE);
 
     // Release cron semaphore
     variable_del('cron_semaphore');
@@ -2079,7 +2079,7 @@ function drupal_cron_run() {
 function drupal_cron_cleanup() {
   // See if the semaphore is still locked.
   if (variable_get('cron_semaphore', FALSE)) {
-    watchdog('cron', t('Cron run exceeded the time limit and was aborted.'), WATCHDOG_WARNING);
+    watchdog('cron', 'Cron run exceeded the time limit and was aborted.', array(), WATCHDOG_WARNING);
 
     // Release cron semaphore
     variable_del('cron_semaphore');
diff --git a/includes/file.inc b/includes/file.inc
index 7e70ed882c5..1673b75da74 100644
--- a/includes/file.inc
+++ b/includes/file.inc
@@ -107,7 +107,7 @@ function file_check_directory(&$directory, $mode = 0, $form_item = NULL) {
     }
     else {
       form_set_error($form_item, t('The directory %directory is not writable', array('%directory' => $directory)));
-      watchdog('file system', t('The directory %directory is not writable, because it does not have the correct permissions set.', array('%directory' => $directory)), WATCHDOG_ERROR);
+      watchdog('file system', 'The directory %directory is not writable, because it does not have the correct permissions set.', array('%directory' => $directory), WATCHDOG_ERROR);
       return FALSE;
     }
   }
@@ -119,9 +119,9 @@ function file_check_directory(&$directory, $mode = 0, $form_item = NULL) {
       chmod($directory .'/.htaccess', 0664);
     }
     else {
-      $message = t("Security warning: Couldn't write .htaccess file. Please create a .htaccess file in your %directory directory which contains the following lines: <code>!htaccess</code>", array('%directory' => $directory, '!htaccess' => '<br />'. nl2br(check_plain($htaccess_lines))));
-      form_set_error($form_item, $message);
-      watchdog('security', $message, WATCHDOG_ERROR);
+      $variables = array('%directory' => $directory, '!htaccess' => '<br />'. nl2br(check_plain($htaccess_lines)));
+      form_set_error($form_item, t("Security warning: Couldn't write .htaccess file. Please create a .htaccess file in your %directory directory which contains the following lines: <code>!htaccess</code>", $variables));
+      watchdog('security', "Security warning: Couldn't write .htaccess file. Please create a .htaccess file in your %directory directory which contains the following lines: <code>!htaccess</code>", $variables, WATCHDOG_ERROR);
     }
   }
 
@@ -239,7 +239,7 @@ function file_check_upload($source = 'upload') {
     // This overcomes open_basedir restrictions for future file operations.
     if (!move_uploaded_file($_FILES["files"]["tmp_name"][$source], $file->filepath)) {
       drupal_set_message(t('File upload error. Could not move uploaded file.'));
-      watchdog('file', t('Upload Error. Could not move uploaded file (%file) to destination (%destination).', array('%file' => $_FILES["files"]["tmp_name"][$source], '%destination' => $file->filepath)));
+      watchdog('file', 'Upload Error. Could not move uploaded file (%file) to destination (%destination).', array('%file' => $_FILES["files"]["tmp_name"][$source], '%destination' => $file->filepath));
       return FALSE;
     }
 
@@ -320,7 +320,7 @@ function file_copy(&$source, $dest = 0, $replace = FILE_EXISTS_RENAME) {
   if ($basename === FALSE) {
     $source = is_object($source) ? $source->filepath : $source;
     drupal_set_message(t('The selected file %file could not be uploaded, because the destination %directory is not properly configured.', array('%file' => $source, '%directory' => $dest)), 'error');
-    watchdog('file system', t('The selected file %file could not be uploaded, because the destination %directory could not be found, or because its permissions do not allow the file to be written.', array('%file' => $source, '%directory' => $dest)), WATCHDOG_ERROR);
+    watchdog('file system', 'The selected file %file could not be uploaded, because the destination %directory could not be found, or because its permissions do not allow the file to be written.', array('%file' => $source, '%directory' => $dest), WATCHDOG_ERROR);
     return 0;
   }
 
diff --git a/includes/form.inc b/includes/form.inc
index 8a5413272e7..dc843d2868c 100644
--- a/includes/form.inc
+++ b/includes/form.inc
@@ -553,13 +553,13 @@ function _form_validate($elements, $form_id = NULL) {
           foreach ($value as $v) {
             if (!isset($options[$v])) {
               form_error($elements, t('An illegal choice has been detected. Please contact the site administrator.'));
-              watchdog('form', t('Illegal choice %choice in !name element.', array('%choice' => $v, '!name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title'])), WATCHDOG_ERROR);
+              watchdog('form', 'Illegal choice %choice in !name element.', array('%choice' => $v, '!name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title']), WATCHDOG_ERROR);
             }
           }
         }
         elseif (!isset($options[$elements['#value']])) {
           form_error($elements, t('An illegal choice has been detected. Please contact the site administrator.'));
-          watchdog('form', t('Illegal choice %choice in %name element.', array('%choice' => $elements['#value'], '%name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title'])), WATCHDOG_ERROR);
+          watchdog('form', 'Illegal choice %choice in %name element.', array('%choice' => $elements['#value'], '%name' => empty($elements['#title']) ? $elements['#parents'][0] : $elements['#title']), WATCHDOG_ERROR);
         }
       }
     }
diff --git a/includes/image.inc b/includes/image.inc
index 01db0c5e158..6f20c082d8f 100644
--- a/includes/image.inc
+++ b/includes/image.inc
@@ -58,7 +58,7 @@ function image_toolkit_invoke($method, $params = array()) {
       return call_user_func_array($function, $params);
     }
     else {
-      watchdog('php', t("The selected image handling toolkit %toolkit can not correctly process %function.", array('%toolkit' => $toolkit, '%function' => $function)), WATCHDOG_ERROR);
+      watchdog('php', 'The selected image handling toolkit %toolkit can not correctly process %function.', array('%toolkit' => $toolkit, '%function' => $function), WATCHDOG_ERROR);
       return FALSE;
     }
   }
diff --git a/includes/locale.inc b/includes/locale.inc
index e9f60f627c6..fd9cbdcaab9 100644
--- a/includes/locale.inc
+++ b/includes/locale.inc
@@ -50,7 +50,7 @@ function _locale_add_language($code, $name, $native, $direction = 0, $domain = '
     drupal_set_message(t('The language %language has been created.', array('%language' => t($name))));
   }
 
-  watchdog('locale', t('The %language language (%code) has been created.', array('%language' => t($name), '%code' => $code)));
+  watchdog('locale', 'The %language language (%code) has been created.', array('%language' => $name, '%code' => $code));
 }
 
 /**
@@ -457,9 +457,9 @@ function _locale_admin_import_submit($form_id, $form_values) {
 
     // Now import strings into the language
     if ($ret = _locale_import_po($file, $form_values['langcode'], $form_values['mode']) == FALSE) {
-      $message = t('The translation import of %filename failed.', array('%filename' => $file->filename));
-      drupal_set_message($message, 'error');
-      watchdog('locale', $message, WATCHDOG_ERROR);
+      $variables = array('%filename' => $file->filename);
+      drupal_set_message(t('The translation import of %filename failed.', $variables), 'error');
+      watchdog('locale', 'The translation import of %filename failed.', $variables, WATCHDOG_ERROR);
     }
   }
   else {
@@ -704,7 +704,7 @@ function _locale_import_po($file, $lang, $mode) {
   menu_rebuild();
 
   drupal_set_message(t('The translation was successfully imported. There are %number newly created translated strings and %update strings were updated.', array('%number' => $additions, '%update' => $updates)));
-  watchdog('locale', t('Imported %file into %locale: %number new strings added and %update updated.', array('%file' => $file->filename, '%locale' => $lang, '%number' => $additions, '%update' => $updates)));
+  watchdog('locale', 'Imported %file into %locale: %number new strings added and %update updated.', array('%file' => $file->filename, '%locale' => $lang, '%number' => $additions, '%update' => $updates));
   return TRUE;
 }
 
@@ -1353,7 +1353,7 @@ function _locale_export_po($language = NULL) {
       $header .= "\"Plural-Forms: nplurals=". $meta->plurals ."; plural=". strtr($meta->formula, array('$' => '')) .";\\n\"\n";
     }
     $header .= "\n";
-    watchdog('locale', t('Exported %locale translation file: %filename.', array('%locale' => $meta->name, '%filename' => $filename)));
+    watchdog('locale', 'Exported %locale translation file: %filename.', array('%locale' => $meta->name, '%filename' => $filename));
   }
 
   // Generating Portable Object Template
@@ -1374,7 +1374,7 @@ function _locale_export_po($language = NULL) {
     $header .= "\"Content-Transfer-Encoding: 8bit\\n\"\n";
     $header .= "\"Plural-Forms: nplurals=INTEGER; plural=EXPRESSION;\\n\"\n";
     $header .= "\n";
-    watchdog('locale', t('Exported translation file: %filename.', array('%filename' => $filename)));
+    watchdog('locale', 'Exported translation file: %filename.', array('%filename' => $filename));
   }
 
   // Start download process
diff --git a/includes/unicode.inc b/includes/unicode.inc
index 7f546d4f9c0..93ec8177213 100644
--- a/includes/unicode.inc
+++ b/includes/unicode.inc
@@ -148,7 +148,7 @@ function drupal_xml_parser_create(&$data) {
       $data = ereg_replace('^(<\?xml[^>]+encoding)="([^"]+)"', '\\1="utf-8"', $out);
     }
     else {
-      watchdog('php', t("Could not convert XML encoding %s to UTF-8.", array('%s' => $encoding)), WATCHDOG_WARNING);
+      watchdog('php', 'Could not convert XML encoding %s to UTF-8.', array('%s' => $encoding), WATCHDOG_WARNING);
       return 0;
     }
   }
@@ -181,7 +181,7 @@ function drupal_convert_to_utf8($data, $encoding) {
     $out = @recode_string($encoding .'..utf-8', $data);
   }
   else {
-    watchdog('php', t("Unsupported encoding %s. Please install iconv, GNU recode or mbstring for PHP.", array('%s' => $encoding)), WATCHDOG_ERROR);
+    watchdog('php', 'Unsupported encoding %s. Please install iconv, GNU recode or mbstring for PHP.', array('%s' => $encoding), WATCHDOG_ERROR);
     return FALSE;
   }
 
diff --git a/modules/aggregator/aggregator.module b/modules/aggregator/aggregator.module
index ead329dad50..a544a286e21 100644
--- a/modules/aggregator/aggregator.module
+++ b/modules/aggregator/aggregator.module
@@ -395,7 +395,7 @@ function aggregator_form_category_submit($form_id, $form_values) {
       }
     }
     else {
-      watchdog('aggregator', t('Category %category deleted.', array('%category' => $title)));
+      watchdog('aggregator', 'Category %category deleted.', array('%category' => $title));
       drupal_set_message(t('The category %category has been deleted.', array('%category' => $title)));
       if (arg(0) == 'admin') {
         return 'admin/content/aggregator/';
@@ -406,7 +406,7 @@ function aggregator_form_category_submit($form_id, $form_values) {
     }
   }
   else {
-    watchdog('aggregator', t('Category %category added.', array('%category' => $form_values['title'])), WATCHDOG_NOTICE, l(t('view'), 'admin/content/aggregator'));
+    watchdog('aggregator', 'Category %category added.', array('%category' => $form_values['title']), WATCHDOG_NOTICE, l(t('view'), 'admin/content/aggregator'));
     drupal_set_message(t('The category %category has been added.', array('%category' => $form_values['title'])));
   }
 }
@@ -531,7 +531,7 @@ function aggregator_form_feed_submit($form_id, $form_values) {
       }
     }
     else {
-      watchdog('aggregator', t('Feed %feed deleted.', array('%feed' => $title)));
+      watchdog('aggregator', 'Feed %feed deleted.', array('%feed' => $title));
       drupal_set_message(t('The feed %feed has been deleted.', array('%feed' => $title)));
       if (arg(0) == 'admin') {
         return 'admin/content/aggregator/';
@@ -542,7 +542,7 @@ function aggregator_form_feed_submit($form_id, $form_values) {
     }
   }
   else {
-    watchdog('aggregator', t('Feed %feed added.', array('%feed' => $form_values['title'])), WATCHDOG_NOTICE, l(t('view'), 'admin/content/aggregator'));
+    watchdog('aggregator', 'Feed %feed added.', array('%feed' => $form_values['title']), WATCHDOG_NOTICE, l(t('view'), 'admin/content/aggregator'));
     drupal_set_message(t('The feed %feed has been added.', array('%feed' => $form_values['title'])));
   }
 }
@@ -731,7 +731,7 @@ function aggregator_refresh($feed) {
       break;
     case 301:
       $feed['url'] = $result->redirect_url;
-      watchdog('aggregator', t('Updated URL for feed %title to %url.', array('%title' => $feed['title'], '%url' => $feed['url'])));
+      watchdog('aggregator', 'Updated URL for feed %title to %url.', array('%title' => $feed['title'], '%url' => $feed['url']));
 
     case 200:
     case 302:
@@ -779,12 +779,12 @@ function aggregator_refresh($feed) {
 
         cache_clear_all();
 
-        watchdog('aggregator', t('There is new syndicated content from %site.', array('%site' => $feed['title'])));
+        watchdog('aggregator', 'There is new syndicated content from %site.', array('%site' => $feed['title']));
         drupal_set_message(t('There is new syndicated content from %site.', array('%site' => $feed['title'])));
       }
       break;
     default:
-      watchdog('aggregator', t('The feed from %site seems to be broken, due to "%error".', array('%site' => $feed['title'], '%error' => $result->code .' '. $result->error)), WATCHDOG_WARNING);
+      watchdog('aggregator', 'The feed from %site seems to be broken, due to "%error".', array('%site' => $feed['title'], '%error' => $result->code .' '. $result->error), WATCHDOG_WARNING);
       drupal_set_message(t('The feed from %site seems to be broken, because of error "%error".', array('%site' => $feed['title'], '%error' => $result->code .' '. $result->error)));
   }
 }
@@ -841,7 +841,7 @@ function aggregator_parse_feed(&$data, $feed) {
   xml_set_character_data_handler($xml_parser, 'aggregator_element_data');
 
   if (!xml_parse($xml_parser, $data, 1)) {
-    watchdog('aggregator', t('The feed from %site seems to be broken, due to an error "%error" on line %line.', array('%site' => $feed['title'], '%error' => xml_error_string(xml_get_error_code($xml_parser)), '%line' => xml_get_current_line_number($xml_parser))), WATCHDOG_WARNING);
+    watchdog('aggregator', 'The feed from %site seems to be broken, due to an error "%error" on line %line.', array('%site' => $feed['title'], '%error' => xml_error_string(xml_get_error_code($xml_parser)), '%line' => xml_get_current_line_number($xml_parser)), WATCHDOG_WARNING);
     drupal_set_message(t('The feed from %site seems to be broken, because of error "%error" on line %line.', array('%site' => $feed['title'], '%error' => xml_error_string(xml_get_error_code($xml_parser)), '%line' => xml_get_current_line_number($xml_parser))), 'error');
     return 0;
   }
diff --git a/modules/blogapi/blogapi.module b/modules/blogapi/blogapi.module
index fa6cfc0faf0..d003ff42125 100644
--- a/modules/blogapi/blogapi.module
+++ b/modules/blogapi/blogapi.module
@@ -218,7 +218,7 @@ function blogapi_blogger_new_post($appkey, $blogid, $username, $password, $conte
   $node = node_submit($edit);
   node_save($node);
   if ($node->nid) {
-    watchdog('content', t('@type: added %title using blog API.', array('@type' => t($node->type), '%title' => $node->title)), WATCHDOG_NOTICE, l(t('view'), "node/$node->nid"));
+    watchdog('content', '@type: added %title using blog API.', array('@type' => $node->type, '%title' => $node->title), WATCHDOG_NOTICE, l(t('view'), "node/$node->nid"));
     // blogger.newPost returns a string so we cast the nid to a string by putting it in double quotes:
     return "$node->nid";
   }
@@ -274,7 +274,7 @@ function blogapi_blogger_edit_post($appkey, $postid, $username, $password, $cont
   $node = node_submit($node);
   node_save($node);
   if ($node->nid) {
-    watchdog('content', t('@type: updated %title using blog API.', array('@type' => t($node->type), '%title' => $node->title)), WATCHDOG_NOTICE, l(t('view'), "node/$node->nid"));
+    watchdog('content', '@type: updated %title using blog API.', array('@type' => $node->type, '%title' => $node->title), WATCHDOG_NOTICE, l(t('view'), "node/$node->nid"));
     return TRUE;
   }
 
diff --git a/modules/book/book.module b/modules/book/book.module
index 9451e623d36..5c1c2e0bd77 100644
--- a/modules/book/book.module
+++ b/modules/book/book.module
@@ -939,7 +939,7 @@ function book_admin_edit_submit($form_id, $form_values) {
       $node->weight = $row['weight'];
 
       node_save($node);
-      watchdog('content', t('%type: updated %title.', array('%type' => t('book'), '%title' => $node->title)), WATCHDOG_NOTICE, l(t('view'), 'node/'. $node->nid));
+      watchdog('content', 'book: updated %title.', array('%title' => $node->title), WATCHDOG_NOTICE, l(t('view'), 'node/'. $node->nid));
     }
   }
 
diff --git a/modules/contact/contact.module b/modules/contact/contact.module
index 23d4e3cdfc3..cb3f7712ac3 100644
--- a/modules/contact/contact.module
+++ b/modules/contact/contact.module
@@ -243,13 +243,13 @@ function contact_admin_edit_submit($form_id, $form_values) {
   if (arg(3) == 'add') {
     db_query("INSERT INTO {contact} (category, recipients, reply, weight, selected) VALUES ('%s', '%s', '%s', %d, %d)", $form_values['category'], $form_values['recipients'], $form_values['reply'], $form_values['weight'], $form_values['selected']);
     drupal_set_message(t('Category %category has been added.', array('%category' => $form_values['category'])));
-    watchdog('mail', t('Contact form: category %category added.', array('%category' => $form_values['category'])), WATCHDOG_NOTICE, l(t('view'), 'admin/build/contact'));
+    watchdog('mail', 'Contact form: category %category added.', array('%category' => $form_values['category']), WATCHDOG_NOTICE, l(t('view'), 'admin/build/contact'));
 
   }
   else {
     db_query("UPDATE {contact} SET category = '%s', recipients = '%s', reply = '%s', weight = %d, selected = %d WHERE cid = %d", $form_values['category'], $form_values['recipients'], $form_values['reply'], $form_values['weight'], $form_values['selected'], $form_values['cid']);
     drupal_set_message(t('Category %category has been updated.', array('%category' => $form_values['category'])));
-    watchdog('mail', t('Contact form: category %category updated.', array('%category' => $form_values['category'])), WATCHDOG_NOTICE, l(t('view'), 'admin/build/contact'));
+    watchdog('mail', 'Contact form: category %category updated.', array('%category' => $form_values['category']), WATCHDOG_NOTICE, l(t('view'), 'admin/build/contact'));
   }
 
   return 'admin/build/contact';
@@ -278,7 +278,7 @@ function contact_admin_delete($cid = NULL) {
 function contact_admin_delete_submit($form_id, $form_values) {
   db_query("DELETE FROM {contact} WHERE cid = %d", arg(4));
   drupal_set_message(t('Category %category has been deleted.', array('%category' => $form_values['category'])));
-  watchdog('mail', t('Contact form: category %category deleted.', array('%category' => $form_values['category'])), WATCHDOG_NOTICE);
+  watchdog('mail', 'Contact form: category %category deleted.', array('%category' => $form_values['category']), WATCHDOG_NOTICE);
 
   return 'admin/build/contact';
 }
@@ -393,7 +393,7 @@ function contact_mail_user_submit($form_id, $form_values) {
 
   // Log the operation:
   flood_register_event('contact');
-  watchdog('mail', t('%name-from sent %name-to an e-mail.', array('%name-from' => $user->name, '%name-to' => $account->name)));
+  watchdog('mail', '%name-from sent %name-to an e-mail.', array('%name-from' => $user->name, '%name-to' => $account->name));
 
   // Set a status message:
   drupal_set_message(t('The message has been sent.'));
@@ -544,7 +544,7 @@ function contact_mail_page_submit($form_id, $form_values) {
 
   // Log the operation:
   flood_register_event('contact');
-  watchdog('mail', t('%name-from sent an e-mail regarding %category.', array('%name-from' => $form_values['name'] ." <$from>", '%category' => $contact->category)));
+  watchdog('mail', '%name-from sent an e-mail regarding %category.', array('%name-from' => $form_values['name'] ." <$from>", '%category' => $contact->category));
 
   // Update user:
   drupal_set_message(t('Your message has been sent.'));
diff --git a/modules/dblog/dblog.install b/modules/dblog/dblog.install
index f94bab65110..44961f7b13b 100644
--- a/modules/dblog/dblog.install
+++ b/modules/dblog/dblog.install
@@ -13,6 +13,7 @@ function dblog_install() {
         uid int NOT NULL default '0',
         type varchar(16) NOT NULL default '',
         message longtext NOT NULL,
+        variables longtext NOT NULL,
         severity tinyint unsigned NOT NULL default '0',
         link varchar(255) NOT NULL default '',
         location text NOT NULL,
@@ -30,6 +31,7 @@ function dblog_install() {
         uid int NOT NULL default '0',
         type varchar(16) NOT NULL default '',
         message text NOT NULL,
+        variables text NOT NULL,
         severity smallint_unsigned NOT NULL default '0',
         link varchar(255) NOT NULL default '',
         location text NOT NULL default '',
diff --git a/modules/dblog/dblog.module b/modules/dblog/dblog.module
index 6af3d26137d..ad72a5e7bf0 100644
--- a/modules/dblog/dblog.module
+++ b/modules/dblog/dblog.module
@@ -159,12 +159,12 @@ function dblog_overview() {
     ' ',
     array('data' => t('Type'), 'field' => 'w.type'),
     array('data' => t('Date'), 'field' => 'w.wid', 'sort' => 'desc'),
-    array('data' => t('Message'), 'field' => 'w.message'),
+    t('Message'),
     array('data' => t('User'), 'field' => 'u.name'),
     array('data' => t('Operations'))
   );
 
-  $sql = "SELECT w.wid, w.uid, w.severity, w.type, w.timestamp, w.message, w.link, u.name FROM {watchdog} w INNER JOIN {users} u ON w.uid = u.uid";
+  $sql = "SELECT w.wid, w.uid, w.severity, w.type, w.timestamp, w.message, w.variables, w.link, u.name FROM {watchdog} w INNER JOIN {users} u ON w.uid = u.uid";
   $tablesort = tablesort_sql($header);
   $type = $_SESSION['dblog_overview_filter'];
   if ($type != 'all') {
@@ -181,7 +181,7 @@ function dblog_overview() {
         $icons[$dblog->severity],
         t($dblog->type),
         format_date($dblog->timestamp, 'small'),
-        l(truncate_utf8($dblog->message, 56, TRUE, TRUE), 'admin/logs/event/'. $dblog->wid, array('html' => TRUE)),
+        l(truncate_utf8(_dblog_format_message($dblog), 56, TRUE, TRUE), 'admin/logs/event/'. $dblog->wid, array('html' => TRUE)),
         theme('username', $dblog),
         $dblog->link,
       ),
@@ -211,11 +211,11 @@ function dblog_top($type) {
     array('data' => t('Message'), 'field' => 'message')
   );
 
-  $result = pager_query("SELECT COUNT(wid) AS count, message FROM {watchdog} WHERE type = '%s' GROUP BY message ". tablesort_sql($header), 30, 0, "SELECT COUNT(DISTINCT(message)) FROM {watchdog} WHERE type = '%s'", $type);
+  $result = pager_query("SELECT COUNT(wid) AS count, message, variables FROM {watchdog} WHERE type = '%s' GROUP BY message ". tablesort_sql($header), 30, 0, "SELECT COUNT(DISTINCT(message)) FROM {watchdog} WHERE type = '%s'", $type);
 
   $rows = array();
   while ($dblog = db_fetch_object($result)) {
-    $rows[] = array($dblog->count, truncate_utf8($dblog->message, 56, TRUE, TRUE));
+    $rows[] = array($dblog->count, truncate_utf8(_dblog_format_message($dblog), 56, TRUE, TRUE));
   }
 
   if (empty($rows)) {
@@ -267,7 +267,7 @@ function dblog_event($id) {
       ),
       array(
         array('data' => t('Message'), 'header' => TRUE),
-        $dblog->message,
+        _dblog_format_message($dblog),
       ),
       array(
         array('data' => t('Severity'), 'header' => TRUE),
@@ -302,12 +302,13 @@ function _dblog_get_message_types() {
 function dblog_watchdog($log = array()) {
   $current_db = db_set_active();
   db_query("INSERT INTO {watchdog}
-    (uid, type, message, severity, link, location, referer, hostname, timestamp)
+    (uid, type, message, variables, severity, link, location, referer, hostname, timestamp)
     VALUES
-    (%d, '%s', '%s', %d, '%s', '%s', '%s', '%s', %d)",
+    (%d, '%s', '%s', '%s', %d, '%s', '%s', '%s', '%s', %d)",
     $log['user']->uid,
     $log['type'],
     $log['message'],
+    serialize($log['variables']),
     $log['severity'],
     $log['link'],
     $log['request_uri'],
@@ -319,3 +320,20 @@ function dblog_watchdog($log = array()) {
     db_set_active($current_db);
   }
 }
+
+/**
+ * Formats a log message for display.
+ *
+ * @param $dblog
+ *   An object with at least the message and variables properties
+ */
+function _dblog_format_message($dblog) {
+  // Legacy messages and user specified text
+  if ($dblog->variables === 'N;') {
+    return $dblog->message;
+  }
+  // Message to translate with injected variables
+  else {
+    return t($dblog->message, unserialize($dblog->variables));
+  }
+}
diff --git a/modules/drupal/drupal.module b/modules/drupal/drupal.module
index 980467109ad..a75b484789a 100644
--- a/modules/drupal/drupal.module
+++ b/modules/drupal/drupal.module
@@ -205,7 +205,7 @@ function drupal_client_ping($client, $system) {
         db_query("INSERT INTO {client_system} (cid, name, type) VALUES (%d, '%s', '%s')", $client['cid'], $item['name'], $item['type']);
       }
     }
-    watchdog('client ping', t('Ping from %name (%link).', array('%name' => $client['name'], '%link' => $client['link'])), WATCHDOG_NOTICE, '<a href="'. check_url($client['link']) .'">view</a>');
+    watchdog('client ping', 'Ping from %name (%link).', array('%name' => $client['name'], '%link' => $client['link']), WATCHDOG_NOTICE, '<a href="'. check_url($client['link']) .'">view</a>');
 
     return TRUE;
   }
@@ -300,7 +300,7 @@ function drupal_notify($server) {
   $result = xmlrpc($server, 'drupal.client.ping', $client, $system);
 
   if ($result === FALSE) {
-    watchdog('server ping', t('Failed to notify %server; error code: %errno; error message: %error_msg.', array('%server' => $server, '%errno' => xmlrpc_errno(), '%error_msg' => xmlrpc_error_msg())), WATCHDOG_WARNING);
+    watchdog('server ping', 'Failed to notify %server; error code: %errno; error message: %error_msg.', array('%server' => $server, '%errno' => xmlrpc_errno(), '%error_msg' => xmlrpc_error_msg()), WATCHDOG_WARNING);
   }
 }
 
diff --git a/modules/filter/filter.module b/modules/filter/filter.module
index 93c3e7c1f4b..3b12f637136 100644
--- a/modules/filter/filter.module
+++ b/modules/filter/filter.module
@@ -819,7 +819,7 @@ function filter_form_validate($form) {
     }
   }
   form_error($form, t('An illegal choice has been detected. Please contact the site administrator.'));
-  watchdog('form', t('Illegal choice %choice in %name element.', array('%choice' => $form[$key]['#value'], '%name' => empty($form['#title']) ? $form['#parents'][0] : $form['#title'])), WATCHDOG_ERROR);
+  watchdog('form', 'Illegal choice %choice in %name element.', array('%choice' => $form[$key]['#value'], '%name' => empty($form['#title']) ? $form['#parents'][0] : $form['#title']), WATCHDOG_ERROR);
 }
 
 /**
diff --git a/modules/forum/forum.module b/modules/forum/forum.module
index ac6bb27cc17..8cc65f98bb8 100644
--- a/modules/forum/forum.module
+++ b/modules/forum/forum.module
@@ -615,7 +615,7 @@ function forum_confirm_delete($tid) {
 function forum_confirm_delete_submit($form_id, $form_values) {
   taxonomy_del_term($form_values['tid']);
   drupal_set_message(t('The forum %term and all sub-forums and associated posts have been deleted.', array('%term' => $form_values['name'])));
-  watchdog('content', t('forum: deleted %term and all its sub-forums and associated posts.', array('%term' => $form_values['name'])));
+  watchdog('content', 'forum: deleted %term and all its sub-forums and associated posts.', array('%term' => $form_values['name']));
 
   return 'admin/content/forum';
 }
diff --git a/modules/locale/locale.module b/modules/locale/locale.module
index a3d0438d341..e8233ce0e7a 100644
--- a/modules/locale/locale.module
+++ b/modules/locale/locale.module
@@ -383,9 +383,9 @@ function locale_admin_manage_delete_form_submit($form_id, $form_values) {
   if (isset($languages[$form_values['langcode']])) {
     db_query("DELETE FROM {languages} WHERE language = '%s'", $form_values['langcode']);
     db_query("DELETE FROM {locales_target} WHERE language = '%s'", $form_values['langcode']);
-    $message = t('The language %locale has been removed.', array('%locale' => t($languages[$form_values['langcode']]->name)));
-    drupal_set_message($message);
-    watchdog('locale', $message);
+    $variables = array('%locale' => $languages[$form_values['langcode']]->name);
+    drupal_set_message(t('The language %locale has been removed.', $variables));
+    watchdog('locale', 'The language %locale has been removed.', $variables);
   }
 
   // Changing the locale settings impacts the interface:
diff --git a/modules/menu/menu.module b/modules/menu/menu.module
index 94450391942..0f97771ee38 100644
--- a/modules/menu/menu.module
+++ b/modules/menu/menu.module
@@ -423,7 +423,7 @@ function menu_edit_item_save($edit) {
   else {
     db_query("INSERT INTO {menu_custom} (parent, path, title, description, weight, type, admin) VALUES ('%s', '%s', '%s', '%s', %d, %d, %d)", $parent, isset($edit['path']) ? $edit['path'] : $edit['original_path'], $edit['title'], $edit['description'], $edit['weight'], $edit['type'], isset($edit['path']));
   }
-  watchdog('menu', t('Saved menu item %title.', $t_args), WATCHDOG_NOTICE, l(t('view'), 'admin/build/menu'));
+  watchdog('menu', 'Saved menu item %title.', $t_args, WATCHDOG_NOTICE, l(t('view'), 'admin/build/menu'));
   drupal_set_message(t('The menu item %title has been saved.', $t_args));
   menu_rebuild();
 }
@@ -500,11 +500,11 @@ function menu_item_delete_form_submit($form_id, $form_values) {
   $t_args = array('%title' => $form_values['title']);
   if ($form_values['type'] & MENU_IS_ROOT) {
     drupal_set_message(t('The menu %title has been deleted.', $t_args));
-    watchdog('menu', t('Deleted menu %title.', $t_args), WATCHDOG_NOTICE);
+    watchdog('menu', 'Deleted menu %title.', $t_args, WATCHDOG_NOTICE);
   }
   else {
     drupal_set_message(t('The menu item %title has been deleted.', $t_args));
-    watchdog('menu', t('Deleted menu item %title.', $t_args), WATCHDOG_NOTICE);
+    watchdog('menu', 'Deleted menu item %title.', $t_args, WATCHDOG_NOTICE);
   }
 
   return 'admin/build/menu';
diff --git a/modules/node/content_types.inc b/modules/node/content_types.inc
index eef1589aa45..ff19c9c70a1 100644
--- a/modules/node/content_types.inc
+++ b/modules/node/content_types.inc
@@ -333,7 +333,7 @@ function node_type_form_submit($form_id, $form_values) {
   }
   elseif ($status == SAVED_NEW) {
     drupal_set_message(t('The content type %name has been added.', $t_args));
-    watchdog('node', t('Added content type %name.', $t_args), WATCHDOG_NOTICE, l(t('view'), 'admin/content/types'));
+    watchdog('node', 'Added content type %name.', $t_args, WATCHDOG_NOTICE, l(t('view'), 'admin/content/types'));
   }
 
   return 'admin/content/types';
@@ -401,7 +401,7 @@ function node_type_delete_confirm_submit($form_id, $form_values) {
 
   $t_args = array('%name' => $form_values['name']);
   drupal_set_message(t('The content type %name has been deleted.', $t_args));
-  watchdog('menu', t('Deleted content type %name.', $t_args), WATCHDOG_NOTICE);
+  watchdog('menu', 'Deleted content type %name.', $t_args, WATCHDOG_NOTICE);
 
   node_types_rebuild();
   menu_rebuild();
diff --git a/modules/node/node.module b/modules/node/node.module
index 766325645ec..d178e53b218 100644
--- a/modules/node/node.module
+++ b/modules/node/node.module
@@ -1724,7 +1724,7 @@ function node_revision_revert($nid, $revision) {
       node_save($node);
 
       drupal_set_message(t('%title has been reverted back to the revision from %revision-date', array('%revision-date' => format_date($node->revision_timestamp), '%title' => $node->title)));
-      watchdog('content', t('@type: reverted %title revision %revision.', array('@type' => t($node->type), '%title' => $node->title, '%revision' => $revision)));
+      watchdog('content', '@type: reverted %title revision %revision.', array('@type' => $node->type, '%title' => $node->title, '%revision' => $revision));
     }
     else {
       drupal_set_message(t('You tried to revert to an invalid revision.'), 'error');
@@ -1749,7 +1749,7 @@ function node_revision_delete($nid, $revision) {
         db_query("DELETE FROM {node_revisions} WHERE nid = %d AND vid = %d", $nid, $revision);
         node_invoke_nodeapi($node, 'delete revision');
         drupal_set_message(t('Deleted %title revision %revision.', array('%title' => $node->title, '%revision' => $revision)));
-        watchdog('content', t('@type: deleted %title revision %revision.', array('@type' => t($node->type), '%title' => $node->title, '%revision' => $revision)));
+        watchdog('content', '@type: deleted %title revision %revision.', array('@type' => $node->type, '%title' => $node->title, '%revision' => $revision));
       }
 
       else {
@@ -2286,12 +2286,12 @@ function node_form_submit($form_id, $form_values) {
   // Prepare the node's body:
   if ($node->nid) {
     node_save($node);
-    watchdog('content', t('@type: updated %title.', array('@type' => t($node->type), '%title' => $node->title)), WATCHDOG_NOTICE, l(t('view'), 'node/'. $node->nid));
+    watchdog('content', '@type: updated %title.', array('@type' => $node->type, '%title' => $node->title), WATCHDOG_NOTICE, l(t('view'), 'node/'. $node->nid));
     drupal_set_message(t('The %post has been updated.', array('%post' => node_get_types('name', $node))));
   }
   else {
     node_save($node);
-    watchdog('content', t('@type: added %title.', array('@type' => t($node->type), '%title' => $node->title)), WATCHDOG_NOTICE, l(t('view'), "node/$node->nid"));
+    watchdog('content', '@type: added %title.', array('@type' => $node->type, '%title' => $node->title), WATCHDOG_NOTICE, l(t('view'), "node/$node->nid"));
     drupal_set_message(t('Your %post has been created.', array('%post' => node_get_types('name', $node))));
   }
   if ($node->nid) {
@@ -2353,7 +2353,7 @@ function node_delete($nid) {
       search_wipe($node->nid, 'node');
     }
     drupal_set_message(t('%title has been deleted.', array('%title' => $node->title)));
-    watchdog('content', t('@type: deleted %title.', array('@type' => t($node->type), '%title' => $node->title)));
+    watchdog('content', '@type: deleted %title.', array('@type' => $node->type, '%title' => $node->title));
   }
 }
 
diff --git a/modules/ping/ping.module b/modules/ping/ping.module
index 85626d39ba1..025b5da17d2 100644
--- a/modules/ping/ping.module
+++ b/modules/ping/ping.module
@@ -52,7 +52,7 @@ function ping_ping($name = '', $url = '') {
   $result = xmlrpc('http://rpc.pingomatic.com', 'weblogUpdates.ping', $name, $url);
 
   if ($result === FALSE) {
-    watchdog('directory ping', t('Failed to notify pingomatic.com (site).'), WATCHDOG_WARNING);
+    watchdog('directory ping', 'Failed to notify pingomatic.com (site).', WATCHDOG_WARNING);
   }
 }
 
diff --git a/modules/profile/profile.module b/modules/profile/profile.module
index 3c0faa55da0..e023962ff86 100644
--- a/modules/profile/profile.module
+++ b/modules/profile/profile.module
@@ -372,7 +372,7 @@ function profile_field_form_submit($form_id, $form_values) {
     db_query("INSERT INTO {profile_fields} (title, name, explanation, category, type, weight, required, register, visibility, autocomplete, options, page) VALUES ('%s', '%s', '%s', '%s', '%s', %d, %d, %d, %d, %d, '%s', '%s')", $form_values['title'], $form_values['name'], $form_values['explanation'], $form_values['category'], $form_values['type'], $form_values['weight'], $form_values['required'], $form_values['register'], $form_values['visibility'], $form_values['autocomplete'], $form_values['options'], $form_values['page']);
 
     drupal_set_message(t('The field has been created.'));
-    watchdog('profile', t('Profile field %field added under category %category.', array('%field' => $form_values['title'], '%category' => $form_values['category'])), WATCHDOG_NOTICE, l(t('view'), 'admin/user/profile'));
+    watchdog('profile', 'Profile field %field added under category %category.', array('%field' => $form_values['title'], '%category' => $form_values['category']), WATCHDOG_NOTICE, l(t('view'), 'admin/user/profile'));
   }
   else {
     db_query("UPDATE {profile_fields} SET title = '%s', name = '%s', explanation = '%s', category = '%s', weight = %d, required = %d, register = %d, visibility = %d, autocomplete = %d, options = '%s', page = '%s' WHERE fid = %d", $form_values['title'], $form_values['name'], $form_values['explanation'], $form_values['category'], $form_values['weight'], $form_values['required'], $form_values['register'], $form_values['visibility'], $form_values['autocomplete'], $form_values['options'], $form_values['page'], $form_values['fid']);
@@ -413,7 +413,7 @@ function profile_field_delete_submit($form_id, $form_values) {
   cache_clear_all();
 
   drupal_set_message(t('The field %field has been deleted.', array('%field' => $form_values['title'])));
-  watchdog('profile', t('Profile field %field deleted.', array('%field' => $form_values['title'])), WATCHDOG_NOTICE, l(t('view'), 'admin/user/profile'));
+  watchdog('profile', 'Profile field %field deleted.', array('%field' => $form_values['title']), WATCHDOG_NOTICE, l(t('view'), 'admin/user/profile'));
 
   return 'admin/user/profile';
 }
diff --git a/modules/search/search.module b/modules/search/search.module
index 93cfeb0e6e0..be06edcce40 100644
--- a/modules/search/search.module
+++ b/modules/search/search.module
@@ -936,7 +936,7 @@ function search_view($type = 'node') {
     $results = '';
     if (trim($keys)) {
       // Log the search keys:
-      watchdog('search', t('%keys (@type).', array('%keys' => $keys, '@type' => module_invoke($type, 'search', 'name'))), WATCHDOG_NOTICE, l(t('results'), 'search/'. $type .'/'. $keys));
+      watchdog('search', '%keys (@type).', array('%keys' => $keys, '@type' => module_invoke($type, 'search', 'name')), WATCHDOG_NOTICE, l(t('results'), 'search/'. $type .'/'. $keys));
 
       // Collect the search results:
       $results = search_data($keys, $type);
diff --git a/modules/syslog/syslog.module b/modules/syslog/syslog.module
index 74762269707..76ee75e573f 100644
--- a/modules/syslog/syslog.module
+++ b/modules/syslog/syslog.module
@@ -98,7 +98,8 @@ function theme_syslog_format($entry) {
       '@referer_uri' => $entry['referer'],
       '@uid'         => $entry['user']->uid,
       '@link'        => strip_tags($entry['link']),
-      '@message'     => strip_tags($entry['message']),
+      // Keep message English, but replace variable components.
+      '@message'     => strip_tags(strtr($entry['message'], $entry['variables'])),
     ));
   return $message;
 }
diff --git a/modules/system/system.install b/modules/system/system.install
index ab3bb09badb..334ff08c6ec 100644
--- a/modules/system/system.install
+++ b/modules/system/system.install
@@ -2353,7 +2353,7 @@ function system_update_159() {
       }
       else {
         db_query('UPDATE {old_revisions} SET done = 1 WHERE nid = %d', $node->nid);
-        watchdog('php', "Recovering old revisions for node $node->nid failed.", WATCHDOG_WARNING);
+        watchdog('php', "Recovering old revisions for node %nid failed.", array('%nid' => $node->nid), WATCHDOG_WARNING);
       }
     }
   }
@@ -2583,7 +2583,7 @@ function system_update_169() {
     $encoding = db_result(db_query('SHOW server_encoding'));
     if (!in_array(strtolower($encoding), array('unicode', 'utf8'))) {
       $msg = 'Your PostgreSQL database is set up with the wrong character encoding ('. $encoding .'). It is possible it will not work as expected. It is advised to recreate it with UTF-8/Unicode encoding. More information can be found in the <a href="http://www.postgresql.org/docs/7.4/interactive/multibyte.html">PostgreSQL documentation</a>.';
-      watchdog('php', $msg, WATCHDOG_WARNING);
+      watchdog('php', $msg, array(), WATCHDOG_WARNING);
       drupal_set_message($msg, 'status');
     }
   }
@@ -3777,6 +3777,26 @@ function system_update_6009() {
   return $ret;
 }
 
+/**
+ * Add variable replacement for watchdog messages.
+ */
+function system_update_6009() {
+  $ret = array();
+  switch ($GLOBALS['db_type']) {
+    case 'pgsql':
+      db_add_column($ret, 'watchdog', 'variables', 'text', array('not null' => TRUE));
+      break;
+    case 'mysql':
+    case 'mysqli':
+      $ret[] = update_sql("ALTER TABLE {watchdog} ADD variables longtext NOT NULL");
+      break;
+  }
+  // Ensure we have 'N;' (serialize(NULL)) as the default, so existing
+  // log messages will not get translated in the new system.
+  $ret[] = update_sql("UPDATE {watchdog} SET variables = 'N;'");
+  return $ret;
+}
+
 /**
  * @} End of "defgroup updates-5.x-to-6.x"
  * The next series of updates should start at 7000.