diff --git a/simde/x86/avx512/types.h b/simde/x86/avx512/types.h
index 639df2594..739679e1b 100644
--- a/simde/x86/avx512/types.h
+++ b/simde/x86/avx512/types.h
@@ -607,7 +607,7 @@ typedef uint64_t simde__mmask64;
 #endif
 #if !defined(__mmask64) && defined(SIMDE_ENABLE_NATIVE_ALIASES)
   #if !defined(HEDLEY_INTEL_VERSION)
-    #if defined(HEDLEY_GCC_VERSION)
+    #if defined(HEDLEY_GCC_VERSION) || (defined(__clang__) && (__clang_major__ > 3 || (__clang_major__ == 3 && __clang_minor__ >= 6)))
       typedef unsigned long long __mmask64;
     #else
       typedef uint64_t __mmask64;