diff --git a/reactos/include/crt/mingw32/intrin_x86.h b/reactos/include/crt/mingw32/intrin_x86.h
index 509a059d61a..0f3ece2fa5f 100644
--- a/reactos/include/crt/mingw32/intrin_x86.h
+++ b/reactos/include/crt/mingw32/intrin_x86.h
@@ -75,7 +75,7 @@ extern "C" {
 /* TODO: __getcallerseflags but how??? */
 
 /* Maybe the same for x86? */
-#ifdef _x86_64
+#ifdef __x86_64__
 #define _alloca(s) __builtin_alloca(s)
 #endif
 
@@ -109,10 +109,10 @@ __INTRIN_INLINE void _mm_sfence(void)
 	_WriteBarrier();
 }
 
-#ifdef _x86_64
+#ifdef __x86_64__
 __INTRIN_INLINE void __faststorefence(void)
 {
-    long local;
+	long local;
 	__asm__ __volatile__("lock; orl $0, %0;" : : "m"(local));
 }
 #endif
@@ -198,7 +198,7 @@ __INTRIN_INLINE long _InterlockedAnd(volatile long * const value, const long mas
 }
 
 #if defined(_M_AMD64)
-__INTRIN_INLINE long _InterlockedAnd64(volatile long long * const value, const long long mask)
+__INTRIN_INLINE long long _InterlockedAnd64(volatile long long * const value, const long long mask)
 {
 	return __sync_fetch_and_and(value, mask);
 }
@@ -220,7 +220,7 @@ __INTRIN_INLINE long _InterlockedOr(volatile long * const value, const long mask
 }
 
 #if defined(_M_AMD64)
-__INTRIN_INLINE long _InterlockedOr64(volatile long long * const value, const long long mask)
+__INTRIN_INLINE long long _InterlockedOr64(volatile long long * const value, const long long mask)
 {
 	return __sync_fetch_and_or(value, mask);
 }
@@ -241,6 +241,13 @@ __INTRIN_INLINE long _InterlockedXor(volatile long * const value, const long mas
 	return __sync_fetch_and_xor(value, mask);
 }
 
+#if defined(_M_AMD64)
+__INTRIN_INLINE long long _InterlockedXor64(volatile long long * const value, const long long mask)
+{
+	return __sync_fetch_and_xor(value, mask);
+}
+#endif
+
 #else
 
 __INTRIN_INLINE char _InterlockedCompareExchange8(volatile char * const Destination, const char Exchange, const char Comperand)