diff --git a/Contrib/Modern UI/System.nsh b/Contrib/Modern UI/System.nsh
index 779f5bac..2337d3f9 100644
--- a/Contrib/Modern UI/System.nsh	
+++ b/Contrib/Modern UI/System.nsh	
@@ -1113,6 +1113,7 @@
 
   !ifdef MUI_CUSTOMFUNCTION_START
     Call "${MUI_CUSTOMFUNCTION_START}"
+  !endif
 
   FunctionEnd