--- ray/src/common/malloc.c	1995/11/10 17:04:15	2.10
+++ ray/src/common/malloc.c	1998/08/24 15:31:29	2.11
@@ -303,7 +303,7 @@ register unsigned  n;
 	register int	bucket;
 	register unsigned	bsiz;
 
-	if (n < 1<<FIRSTBUCKET)
+	if (n < 1<<FIRSTBUCKET || p == NULL)
 		return;
 #ifdef MSTATS
 	b_nfreed += n;