diff --git a/src/iceberg/util/int128.h b/src/iceberg/util/int128.h
index 8e9d27dc7..3fff02b1c 100644
--- a/src/iceberg/util/int128.h
+++ b/src/iceberg/util/int128.h
@@ -24,11 +24,18 @@
 
 #if defined(_MSC_VER)
 #  include <__msvc_int128.hpp>
+#elif !defined(__GNUC__) && !defined(__clang__)
+#  error "128-bit integer type is not supported on this platform"
+#endif
+
+namespace iceberg {
+
+#if defined(_MSC_VER)
 using int128_t = std::_Signed128;
 using uint128_t = std::_Unsigned128;
-#elif defined(__GNUC__) || defined(__clang__)
+#else
 using int128_t = __int128;
 using uint128_t = unsigned __int128;
-#else
-#  error "128-bit integer type is not supported on this platform"
 #endif
+
+}  // namespace iceberg