diff --git a/parallel_hashmap/phmap_bits.h b/parallel_hashmap/phmap_bits.h
index 1d9c413..5ac5fac 100644
--- a/parallel_hashmap/phmap_bits.h
+++ b/parallel_hashmap/phmap_bits.h
@@ -337,17 +337,10 @@ PHMAP_BASE_INTERNAL_FORCEINLINE int CountTrailingZerosNonZero32(uint32_t n) {
 #endif
 
 #ifdef PHMAP_HAVE_INTRINSIC_INT128
-
-    #if defined(__GNUC__) && !defined(__clang__)
-        #define PHMAP_EXTENSION 
-    #else
-        #define PHMAP_EXTENSION __extension__
-    #endif
-
     inline uint64_t umul128(uint64_t a, uint64_t b, uint64_t* high) 
     {
-        auto result = static_cast<PHMAP_EXTENSION unsigned __int128>(a) * 
-                      static_cast<PHMAP_EXTENSION unsigned __int128>(b);
+        auto result = static_cast<unsigned __extension__ __int128>(a) * 
+                      static_cast<unsigned __extension__ __int128>(b);
         *high = static_cast<uint64_t>(result >> 64);
         return static_cast<uint64_t>(result);
     }