diff --git a/clang/lib/Driver/WindowsToolChain.cpp b/clang/lib/Driver/WindowsToolChain.cpp
index de31e856491d..a1ba7a7008af 100644
--- a/clang/lib/Driver/WindowsToolChain.cpp
+++ b/clang/lib/Driver/WindowsToolChain.cpp
@@ -30,7 +30,7 @@
   #define WIN32_LEAN_AND_MEAN
   #define NOGDI
   #define NOMINMAX
-  #include <Windows.h>
+  #include <windows.h>
 #endif
 
 using namespace clang::driver;