diff --git a/packages/cpp/src/browser/cpp-language-client-contribution.ts b/packages/cpp/src/browser/cpp-language-client-contribution.ts
index 5b066099d5a3a..57210ec4395c8 100644
--- a/packages/cpp/src/browser/cpp-language-client-contribution.ts
+++ b/packages/cpp/src/browser/cpp-language-client-contribution.ts
@@ -67,12 +67,17 @@ export class CppLanguageClientContribution extends BaseLanguageClientContributio
     }
 
     protected get documentSelector() {
+        // This is used (at least) to determine which files, when they are open,
+        // trigger the launch of the C/C++ language server.
         return HEADER_AND_SOURCE_FILE_EXTENSIONS;
     }
 
     protected get globPatterns() {
+        // This is used (at least) to determine which files we watch.  Change
+        // notifications are forwarded to the language server.
         return [
-            '**/*.{' + HEADER_AND_SOURCE_FILE_EXTENSIONS.join() + '}'
+            '**/*.{' + HEADER_AND_SOURCE_FILE_EXTENSIONS.join() + '}',
+            '**/compile_commands.json',
         ];
     }