diff --git a/src/services/codefixes/convertToAsyncFunction.ts b/src/services/codefixes/convertToAsyncFunction.ts
index ba230aa95e4..b12d4daf1c8 100644
--- a/src/services/codefixes/convertToAsyncFunction.ts
+++ b/src/services/codefixes/convertToAsyncFunction.ts
@@ -393,9 +393,10 @@ namespace ts.codefix {
         const shouldReturn = transformer.setOfExpressionsToReturn.get(getNodeId(parent).toString());
         switch (func.kind) {
             case SyntaxKind.NullKeyword:
-                // do not produce a transformed statement for a null or undefined argument
+                // do not produce a transformed statement for a null argument
                 break;
             case SyntaxKind.Identifier:
+                // identifier includes undefined
                 if (!hasArgName) break;
 
                 const synthCall = createCall(getSynthesizedDeepClone(func) as Identifier, /*typeArguments*/ undefined, [argName.identifier]);
diff --git a/src/services/suggestionDiagnostics.ts b/src/services/suggestionDiagnostics.ts
index 3df40c8d9df..66360948ea7 100644
--- a/src/services/suggestionDiagnostics.ts
+++ b/src/services/suggestionDiagnostics.ts
@@ -196,7 +196,7 @@ namespace ts {
     function isFixablePromiseArgument(arg: Expression): boolean {
         switch (arg.kind) {
             case SyntaxKind.NullKeyword:
-            case SyntaxKind.Identifier:
+            case SyntaxKind.Identifier: // identifier includes undefined
             case SyntaxKind.FunctionDeclaration:
             case SyntaxKind.FunctionExpression:
             case SyntaxKind.ArrowFunction: