diff --git a/sys/src/9/port/devssl.c b/sys/src/9/port/devssl.c
index 7e9133e8e..6f2b7e61e 100644
--- a/sys/src/9/port/devssl.c
+++ b/sys/src/9/port/devssl.c
@@ -1439,7 +1439,7 @@ checkdigestb(Dstate *s, Block *bin)
 	*p = n;
 	(*s->hf)(msgid, 4, digest, &ss);
 
-	if(memcmp(digest, bin->rp, s->diglen) != 0)
+	if(tsmemcmp(digest, bin->rp, s->diglen) != 0)
 		error("bad digest");
 }