diff --git a/mingw-w64-headers/include/winnt.h b/mingw-w64-headers/include/winnt.h
index 007539a66..27e02de79 100644
--- a/mingw-w64-headers/include/winnt.h
+++ b/mingw-w64-headers/include/winnt.h
@@ -706,13 +706,13 @@ typedef LONG RTL_REFERENCE_COUNT32, *PRTL_REFERENCE_COUNT32;
 #ifdef __cplusplus
 #define DEFINE_ENUM_FLAG_OPERATORS(ENUMTYPE) \
 extern "C++" { \
-__MINGW_CXX11_CONSTEXPR inline ENUMTYPE operator | (ENUMTYPE a, ENUMTYPE b) { return ENUMTYPE(((int)a) | ((int)b)); } \
-__MINGW_CXX11_CONSTEXPR inline ENUMTYPE &operator |= (ENUMTYPE &a, ENUMTYPE b) { return (ENUMTYPE &)(((int &)a) |= ((int)b)); } \
-__MINGW_CXX11_CONSTEXPR inline ENUMTYPE operator & (ENUMTYPE a, ENUMTYPE b) { return ENUMTYPE(((int)a) & ((int)b)); } \
-__MINGW_CXX11_CONSTEXPR inline ENUMTYPE &operator &= (ENUMTYPE &a, ENUMTYPE b) { return (ENUMTYPE &)(((int &)a) &= ((int)b)); } \
 __MINGW_CXX11_CONSTEXPR inline ENUMTYPE operator ~ (ENUMTYPE a) { return ENUMTYPE(~((int)a)); } \
+__MINGW_CXX11_CONSTEXPR inline ENUMTYPE operator | (ENUMTYPE a, ENUMTYPE b) { return ENUMTYPE(((int)a) | ((int)b)); } \
+__MINGW_CXX11_CONSTEXPR inline ENUMTYPE operator & (ENUMTYPE a, ENUMTYPE b) { return ENUMTYPE(((int)a) & ((int)b)); } \
 __MINGW_CXX11_CONSTEXPR inline ENUMTYPE operator ^ (ENUMTYPE a, ENUMTYPE b) { return ENUMTYPE(((int)a) ^ ((int)b)); } \
-__MINGW_CXX11_CONSTEXPR inline ENUMTYPE &operator ^= (ENUMTYPE &a, ENUMTYPE b) { return (ENUMTYPE &)(((int &)a) ^= ((int)b)); } \
+__MINGW_CXX14_CONSTEXPR inline ENUMTYPE& operator |= (ENUMTYPE& a, ENUMTYPE b) { return a = a | b; } \
+__MINGW_CXX14_CONSTEXPR inline ENUMTYPE& operator &= (ENUMTYPE& a, ENUMTYPE b) { return a = a & b; } \
+__MINGW_CXX14_CONSTEXPR inline ENUMTYPE& operator ^= (ENUMTYPE& a, ENUMTYPE b) { return a = a ^ b; } \
 }
 #else
 #define DEFINE_ENUM_FLAG_OPERATORS(ENUMTYPE) /* */