diff --git a/modules/user.module b/modules/user.module
index 5a0e533688f..f4ebe3fbd16 100644
--- a/modules/user.module
+++ b/modules/user.module
@@ -187,7 +187,7 @@ function user_validate_mail($mail) {
   ** allowed.
   */
 
-  $user = '[a-zA-Z0-9_\-\.]+';
+  $user = '[a-zA-Z0-9_\-\.\+]+';
   $domain = '(?:[a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9]\.?)+';
   $ipv4 = '[0-9]{1,3}(\.[0-9]{1,3}){3}';
   $ipv6 = '[0-9a-fA-F]{1,4}(\:[0-9a-fA-F]{1,4}){7}';
diff --git a/modules/user/user.module b/modules/user/user.module
index 5a0e533688f..f4ebe3fbd16 100644
--- a/modules/user/user.module
+++ b/modules/user/user.module
@@ -187,7 +187,7 @@ function user_validate_mail($mail) {
   ** allowed.
   */
 
-  $user = '[a-zA-Z0-9_\-\.]+';
+  $user = '[a-zA-Z0-9_\-\.\+]+';
   $domain = '(?:[a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9]\.?)+';
   $ipv4 = '[0-9]{1,3}(\.[0-9]{1,3}){3}';
   $ipv6 = '[0-9a-fA-F]{1,4}(\:[0-9a-fA-F]{1,4}){7}';