diff --git a/stdlib/public/runtime/SwiftDtoa.cpp b/stdlib/public/runtime/SwiftDtoa.cpp
index a1720157ee404..d1f3c1cb090e3 100644
--- a/stdlib/public/runtime/SwiftDtoa.cpp
+++ b/stdlib/public/runtime/SwiftDtoa.cpp
@@ -1,4 +1,4 @@
-//===--- SwiftDtoa.c ---------------------------------------------*- c -*-===//
+//===--- SwiftDtoa.cpp ---------------------------------------------*- C++ -*-===//
 //
 // This source file is part of the Swift.org open source project
 //