--- src/emu/hash.c.orig	2011-03-07 16:11:14.356195777 +0100
+++ src/emu/hash.c	2011-03-07 16:11:41.175195902 +0100
@@ -446,6 +446,8 @@
 		hash_base *rhs_hash = rhs.hash(hash->id());
 		if (hash != NULL && rhs_hash != NULL && *hash != *rhs_hash)
 			return false;
+		else if ( hash == NULL || rhs_hash == NULL )
+			return false;
 	}
 
 	// if all shared hashes match, return true