diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index cd90e6f95a4b4..296366bc93d32 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -15392,7 +15392,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 }
                 type = anyType;
             }
-            signature.resolvedReturnType = type;
+            signature.resolvedReturnType ??= type;
         }
         return signature.resolvedReturnType;
     }