diff --git a/config.h b/config.h
index 00e580d0..b4a4bc54 100644
--- a/config.h
+++ b/config.h
@@ -258,8 +258,9 @@ const lword LWORD_MAX = W64LIT(0xffffffffffffffff);
 #else
 	#define CRYPTOPP_NATIVE_DWORD_AVAILABLE 1
 	#if defined(__alpha__) || defined(__ia64__) || defined(_ARCH_PPC64) || defined(__x86_64__) || defined(__mips64) || defined(__sparc64__)
-		#if defined(__GNUC__) && !defined(__INTEL_COMPILER) && !(CRYPTOPP_GCC_VERSION == 40001 && defined(__APPLE__)) && CRYPTOPP_GCC_VERSION >= 30400
+#if defined(__GNUC__) && !defined(__INTEL_COMPILER) && !(CRYPTOPP_GCC_VERSION == 40001 && defined(__APPLE__)) && !(defined(__GNUC__) && CRYPTOPP_GCC_VERSION < 50000 && defined(_ARCH_PPC64)) && CRYPTOPP_GCC_VERSION >= 30400
 			// GCC 4.0.1 on MacOS X is missing __umodti3 and __udivti3
+			// GCC 4.8.3 and bad uint128_t ops on PPC64/POWER7 (Issue 421)
 			// mode(TI) division broken on amd64 with GCC earlier than GCC 3.4
 			typedef word32 hword;
 			typedef word64 word;