diff --git a/src/webkit2-extension.c b/src/webkit2-extension.c
index d15ee19..ad3bdd0 100644
--- a/src/webkit2-extension.c
+++ b/src/webkit2-extension.c
@@ -1350,7 +1350,6 @@ static const JSStaticFunction lightdm_greeter_functions[] = {
 	{"cancel_timed_login",    cancel_autologin_cb,      kJSPropertyAttributeReadOnly},
 	{"login",                 start_session_cb,         kJSPropertyAttributeReadOnly},
 	{"provide_secret",        respond_cb,               kJSPropertyAttributeReadOnly},
-	{"start_authentication",  authenticate_cb,          kJSPropertyAttributeReadOnly},
 	{"start_session_sync",    start_session_cb,         kJSPropertyAttributeReadOnly},
 	/* -------->>> DEPRECATED! <<<---------------------->>> DEPRECATED! <<<---------*/
 	{NULL,                    NULL,                     0}};
diff --git a/themes/_vendor/js/mock.js b/themes/_vendor/js/mock.js
index b382323..c2e4b9b 100644
--- a/themes/_vendor/js/mock.js
+++ b/themes/_vendor/js/mock.js
@@ -26,7 +26,7 @@
  */
 
 
-if ( 'undefined' !== typeof lightdm ) {
+if ( 'lightdm' in window ) {
 	throw new Error('Cannot use LightDM Mock while the greeter is running!');
 }
 
@@ -851,7 +851,7 @@ MockData = () => ({
 });
 
 
-if ( ! lightdm in window ) {
+if ( ! 'lightdm' in window ) {
 	new ConfigFile();
 	new GreeterUtil();
 	new LightDMGreeter();