diff --git a/client/src/common/server.ts b/client/src/common/server.ts
index 3de053d..46d845b 100644
--- a/client/src/common/server.ts
+++ b/client/src/common/server.ts
@@ -91,7 +91,7 @@ async function createServer(
     }
 
     // Options to control the language client
-    const tclFileWatcher = workspace.createFileSystemWatcher("**/*.{tcl,psc}")
+    const tclFileWatcher = workspace.createFileSystemWatcher("**/*.{tcl,psc,def}")
     const clientOptions: LanguageClientOptions = {
         // Register the server for python documents
         documentSelector: isVirtualWorkspace()