diff --git a/src/MimaSim/MimaSim/Controls/ProgramEditorControl.axaml.cs b/src/MimaSim/MimaSim/Controls/ProgramEditorControl.axaml.cs
index 41834161..ee18e5e2 100644
--- a/src/MimaSim/MimaSim/Controls/ProgramEditorControl.axaml.cs
+++ b/src/MimaSim/MimaSim/Controls/ProgramEditorControl.axaml.cs
@@ -35,6 +35,6 @@ private void InitializeComponent()
 
         HighlightingManager.Instance.RegisterHighlighting("Custom Highlighting", new string[] { ".cool" }, customHighlighting);
 
-        editor.SyntaxHighlighting = HighlightingManager.Instance.GetDefinitionByExtension(".cool");
+        editor.SyntaxHighlighting = customHighlighting;
     }
 }
\ No newline at end of file