diff --git a/libcxx/test/support/nasty_macros.hpp b/libcxx/test/support/nasty_macros.hpp
index dc4f18ee8521..ff141f7954c8 100644
--- a/libcxx/test/support/nasty_macros.hpp
+++ b/libcxx/test/support/nasty_macros.hpp
@@ -37,7 +37,13 @@
 #define _Y NASTY_MACRO
 #define _Z NASTY_MACRO
 
-#define _UI NASTY_MACRO // tchar.h defines this on Windows.
+// tchar.h defines these macros on Windows.
+#define _UI   NASTY_MACRO
+#define _PUC  NASTY_MACRO
+#define _CPUC NASTY_MACRO
+#define _PC   NASTY_MACRO
+#define _CRPC NASTY_MACRO
+#define _CPC  NASTY_MACRO
 
 // Test that libc++ doesn't use names reserved by WIN32 API Macros.
 // NOTE: Obviously we can only define these on non-windows platforms.