diff --git a/include/util/ieee754.hpp b/include/util/ieee754.hpp
index a6112ec2f..6b4d88b6a 100644
--- a/include/util/ieee754.hpp
+++ b/include/util/ieee754.hpp
@@ -88,8 +88,9 @@ struct DiyFp
             h++;
         return DiyFp(h, e + rhs.e + 64);
 #elif (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)) && defined(__x86_64__)
-        unsigned __int128 p =
-            static_cast<unsigned __int128>(f) * static_cast<unsigned __int128>(rhs.f);
+        __extension__ using uint128 = unsigned __int128;
+        uint128 p =
+            static_cast<uint128>(f) * static_cast<uint128>(rhs.f);
         uint64_t h = p >> 64;
         uint64_t l = static_cast<uint64_t>(p);
         if (l & (uint64_t(1) << 63)) // rounding