diff --git a/extensions/typescript-language-features/src/languageFeatures/completions.ts b/extensions/typescript-language-features/src/languageFeatures/completions.ts
index 989e498bad3..73f54f20c69 100644
--- a/extensions/typescript-language-features/src/languageFeatures/completions.ts
+++ b/extensions/typescript-language-features/src/languageFeatures/completions.ts
@@ -434,7 +434,7 @@ class TypeScriptCompletionItemProvider implements vscode.CompletionItemProvider<
 		position: vscode.Position,
 		token: vscode.CancellationToken,
 		context: vscode.CompletionContext
-	): Promise<vscode.CompletionList<MyCompletionItem> | null> {
+	): Promise<vscode.CompletionList<MyCompletionItem> | undefined> {
 		if (this.typingsStatus.isAcquiringTypings) {
 			return Promise.reject<vscode.CompletionList<MyCompletionItem>>({
 				label: localize(
@@ -448,14 +448,14 @@ class TypeScriptCompletionItemProvider implements vscode.CompletionItemProvider<
 
 		const file = this.client.toOpenedFilePath(document);
 		if (!file) {
-			return null;
+			return undefined;
 		}
 
 		const line = document.lineAt(position.line);
 		const completionConfiguration = CompletionConfiguration.getConfigurationForResource(this.modeId, document.uri);
 
 		if (!this.shouldTrigger(context, line, position)) {
-			return null;
+			return undefined;
 		}
 
 		const wordRange = document.getWordRangeAtPosition(position);
@@ -487,7 +487,7 @@ class TypeScriptCompletionItemProvider implements vscode.CompletionItemProvider<
 
 			if (response.type !== 'response' || !response.body) {
 				this.logCompletionsTelemetry(duration, response);
-				return null;
+				return undefined;
 			}
 			isNewIdentifierLocation = response.body.isNewIdentifierLocation;
 			isMemberCompletion = response.body.isMemberCompletion;
@@ -505,7 +505,7 @@ class TypeScriptCompletionItemProvider implements vscode.CompletionItemProvider<
 		} else {
 			const response = await this.client.interruptGetErr(() => this.client.execute('completions', args, token));
 			if (response.type !== 'response' || !response.body) {
-				return null;
+				return undefined;
 			}
 
 			entries = response.body;