diff --git a/include/msvc_compat/C99/stdbool.h b/include/msvc_compat/C99/stdbool.h
--- a/include/msvc_compat/C99/stdbool.h
+++ b/include/msvc_compat/C99/stdbool.h
@@ -1,16 +1,18 @@
 #ifndef stdbool_h
 #define stdbool_h
 
 #include <wtypes.h>
 
 /* MSVC doesn't define _Bool or bool in C, but does have BOOL */
 /* Note this doesn't pass autoconf's test because (bool) 0.5 != true */
+#ifndef __clang__
 typedef BOOL _Bool;
+#endif
 
 #define bool _Bool
 #define true 1
 #define false 0
 
 #define __bool_true_false_are_defined 1
 
 #endif /* stdbool_h */
