diff --git a/js/server_privileges.js b/js/server_privileges.js
index 8863b4cceb..a564cf9515 100644
--- a/js/server_privileges.js
+++ b/js/server_privileges.js
@@ -165,7 +165,8 @@ function addUser($form)
 /**
  * Unbind all event handlers before tearing down a page
  */
-AJAX.registerTeardown('server_privileges.js', function () {
+AJAX.registerTeardown('server_privileges.js', function() {
+    $("#fieldset_add_user_login input[name='username']").die("focusout");
     $("#fieldset_add_user a.ajax").die("click");
     $('form[name=usersForm]').unbind('submit');
     $("#reload_privileges_anchor.ajax").die("click");
@@ -179,6 +180,31 @@ AJAX.registerTeardown('server_privileges.js', function () {
 });
 
 AJAX.registerOnload('server_privileges.js', function () {
+    /**
+     * Display a warning if there is already a user by the name entered as the username.
+     */
+    $("#fieldset_add_user_login input[name='username']").live("focusout", function() {
+        var username = $(this).val();
+        var $warning = $("#user_exists_warning");
+        if ($("#select_pred_username").val() == 'userdefined' && username != '') {
+            var href = $("form[name='usersForm']").attr('action');
+            var params = {
+                'ajax_request' : true,
+                'token' : PMA_commonParams.get('token'),
+                'validate_username' : true,
+                'username' : username
+            };
+            $.get(href, params, function(data) {
+                if (data['user_exists']) {
+                    $warning.show();
+                } else {
+                    $warning.hide();
+                }
+            });
+        } else {
+            $warning.hide();
+        }
+    });
     /**
      * AJAX event handler for 'Add a New User'
      *
diff --git a/libraries/server_privileges.lib.php b/libraries/server_privileges.lib.php
index 05a8653d71..c30dd34870 100644
--- a/libraries/server_privileges.lib.php
+++ b/libraries/server_privileges.lib.php
@@ -1035,6 +1035,7 @@ function PMA_getHtmlForDisplayLoginInformationFields($mode = 'new')
     $html_output .= '        onchange="'
         . 'if (this.value == \'any\') {'
         . '    username.value = \'\'; '
+        . '    user_exists_warning.style.display = \'none\'; '
         . '} else if (this.value == \'userdefined\') {'
         . '    username.focus(); username.select(); '
         . '}">' . "\n";
@@ -1068,8 +1069,15 @@ function PMA_getHtmlForDisplayLoginInformationFields($mode = 'new')
                : $GLOBALS['username']
            ) . '"'
         )
-        . ' onchange="pred_username.value = \'userdefined\';" />' . "\n"
-        . '</div>' . "\n";
+        . ' onchange="pred_username.value = \'userdefined\';" />' . "\n";
+
+    $html_output .= '<div id="user_exists_warning"'
+        . ' name="user_exists_warning" style="display:none;">'
+        . PMA_Message::notice(
+            __('An account already exists with the same username but possibly a different hostname. Are you sure you wish to proceed?')
+        )->getDisplay()
+        . '</div>';
+    $html_output .= '</div>';
 
     $html_output .= '<div class="item">' . "\n"
         . '<label for="select_pred_hostname">' . "\n"
@@ -1905,6 +1913,19 @@ function PMA_getExtraDataForAjaxBehavior($password, $link_export, $sql_query,
 
         $extra_data['new_privileges'] = $new_privileges;
     }
+
+    if (isset($_REQUEST['validate_username'])) {
+        $sql_query = "SELECT * FROM `mysql`.`user` WHERE `User` = '"
+            . $_REQUEST['username'] . "';";
+        $res = PMA_DBI_query($sql_query);
+        $row = PMA_DBI_fetch_row($res);
+        if (empty($row)) {
+            $extra_data['user_exists'] = false;
+        } else {
+            $extra_data['user_exists'] = true;
+        }
+    }
+
     return $extra_data;
 }
 
diff --git a/server_privileges.php b/server_privileges.php
index 7a94b94ec6..726fc0d0e1 100644
--- a/server_privileges.php
+++ b/server_privileges.php
@@ -356,6 +356,10 @@ if (isset($_REQUEST['flush_privileges'])) {
     $message = PMA_Message::success(__('The privileges were reloaded successfully.'));
 }
 
+if (isset($_REQUEST['validate_username'])) {
+    $message = PMA_Message::success();
+}
+
 /**
  * some standard links
  */