diff --git a/src/vs/workbench/api/common/extHostLanguageFeatures.ts b/src/vs/workbench/api/common/extHostLanguageFeatures.ts
index 19592d3f92e..8f14bc22f4d 100644
--- a/src/vs/workbench/api/common/extHostLanguageFeatures.ts
+++ b/src/vs/workbench/api/common/extHostLanguageFeatures.ts
@@ -1743,7 +1743,7 @@ export class ExtHostLanguageFeatures implements extHostProtocol.ExtHostLanguageF
 
 	registerCompletionItemProvider(extension: IExtensionDescription, selector: vscode.DocumentSelector, provider: vscode.CompletionItemProvider, triggerCharacters: string[]): vscode.Disposable {
 		const handle = this._addNewAdapter(new SuggestAdapter(this._documents, this._commands.converter, provider, this._apiDeprecation, extension), extension);
-		this._proxy.$registerSuggestSupport(handle, this._transformDocumentSelector(selector), triggerCharacters, SuggestAdapter.supportsResolving(provider), `${extension.identifier.value}/${triggerCharacters.join()}`);
+		this._proxy.$registerSuggestSupport(handle, this._transformDocumentSelector(selector), triggerCharacters, SuggestAdapter.supportsResolving(provider), `${extension.identifier.value}(${triggerCharacters.join('')})`);
 		return this._createDisposable(handle);
 	}