diff --git a/crypto/ppccap.c b/crypto/ppccap.c
index 6ccd99185..ab89ccaa1 100644
--- a/crypto/ppccap.c
+++ b/crypto/ppccap.c
@@ -22,7 +22,7 @@ int bn_mul_mont(BN_ULONG *rp, const BN_ULONG *ap, const BN_ULONG *bp, const BN_U
 	if (sizeof(size_t)==4)
 		{
 #if (defined(__APPLE__) && defined(__MACH__))
-		if ((OPENSSL_ppccap_P&PPC_FPU64))
+		if (num>=8 && (num&3)==0 && (OPENSSL_ppccap_P&PPC_FPU64))
 			return bn_mul_mont_fpu64(rp,ap,bp,np,n0,num);
 #else
 		/* boundary of 32 was experimentally determined on