diff --git a/modules/taxonomy/taxonomy.pages.inc b/modules/taxonomy/taxonomy.pages.inc
index 19abf19d4d2..4f9ad5696bb 100644
--- a/modules/taxonomy/taxonomy.pages.inc
+++ b/modules/taxonomy/taxonomy.pages.inc
@@ -91,8 +91,9 @@ function taxonomy_autocomplete($field_name, $tags_typed = '') {
 
     // Part of the criteria for the query come from the field's own settings.
     $vids = array();
+    $vocabularies = taxonomy_vocabulary_get_names();
     foreach ($field['settings']['allowed_values'] as $tree) {
-      $vids[] = $tree['vid'];
+      $vids[] = $vocabularies[$tree['vocabulary']]->vid;
     }
 
     $query = db_select('taxonomy_term_data', 't');
diff --git a/modules/taxonomy/taxonomy.test b/modules/taxonomy/taxonomy.test
index 766e1832f16..31d5ae4e54c 100644
--- a/modules/taxonomy/taxonomy.test
+++ b/modules/taxonomy/taxonomy.test
@@ -466,7 +466,7 @@ class TaxonomyTermTestCase extends TaxonomyWebTestCase {
     $this->drupalGet('node/' . $node->nid);
     $this->assertText($term2->name, t('Term is displayed when viewing the node.'));
 
-    //Preview the node
+    // Preview the node.
     $this->drupalPost('node/' . $node->nid . '/edit', $edit, t('Preview'));
     $this->assertNoUniqueText($term2->name, t('Term is displayed when previewing the node.'));
     $this->drupalPost(NULL, NULL, t('Preview'));
@@ -530,6 +530,11 @@ class TaxonomyTermTestCase extends TaxonomyWebTestCase {
       $this->assertText($term_name, t('The term %name appears on the node page after one term %deleted was deleted', array('%name' => $term_name, '%deleted' => $term1->name)));
     }
     $this->assertNoText($term1->name, t('The deleted term %name does not appear on the node page.', array('%name' => $term1->name)));
+
+    // Test autocomplete on term 2.
+    $input = substr($term2->name, 0, 3);
+    $this->drupalGet('taxonomy/autocomplete/taxonomy_' . $this->vocabulary->machine_name . '/' . $input);
+    $this->assertRaw('{"' . $term2->name . '":"' . $term2->name . '"}', t('Autocomplete returns term %term_name after typing the first 3 letters.', array('%term_name' => $term2->name)));
   }
 
   /**
@@ -586,7 +591,7 @@ class TaxonomyTermTestCase extends TaxonomyWebTestCase {
     $term->description = '';
     taxonomy_term_save($term);
     $this->drupalGet('taxonomy/term/' . $term->tid);
-    $this->assertNoPattern('|class="term-listing-heading"|', 'Term page did not display the term description when description was blank.');    
+    $this->assertNoPattern('|class="term-listing-heading"|', 'Term page did not display the term description when description was blank.');
 
     // Check that the term feed page is working.
     $this->drupalGet('taxonomy/term/' . $term->tid . '/feed');
@@ -1036,7 +1041,7 @@ class TaxonomyTokenReplaceTestCase extends TaxonomyWebTestCase {
     $tests['[term:node-count]'] = 0;
     $tests['[term:parent:name]'] = '[term:parent:name]';
     $tests['[term:vocabulary:name]'] = check_plain($this->vocabulary->name);
-    
+
     foreach ($tests as $input => $expected) {
       $output = token_replace($input, array('term' => $term1), array('language' => $language));
       $this->assertFalse(strcmp($output, $expected), t('Sanitized taxonomy term token %token replaced.', array('%token' => $input)));