diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 307b0850392..6790bcc8f0f 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -37431,8 +37431,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             const [i, type] = predicate;
             const param = func.parameters[i];
             if (isIdentifier(param.name)) {
-                // TODO: is there an alternative to the "as string" here? (It's __String)
-                return createTypePredicate(TypePredicateKind.Identifier, param.name.escapedText as string, i, type);
+                return createTypePredicate(TypePredicateKind.Identifier, unescapeLeadingUnderscores(param.name.escapedText), i, type);
             }
         }
         return undefined;