diff --git a/src/js/filemanager.js b/src/js/filemanager.js
index db6dfb37f..0f328341e 100644
--- a/src/js/filemanager.js
+++ b/src/js/filemanager.js
@@ -757,7 +757,7 @@ app.controller('FileManagerController', ['$scope', '$translate', '$timeout', 'Cl
                 $timeout(function () {
                     $scope.textEditor.unsaved = false;
                     $scope.textEditor.busy = false;
-                    if (callback) return callback();
+                    if (typeof callback === 'function') return callback();
                 }, 1000);
             });
         },