diff --git a/drivers/s390/net/netiucv.c b/drivers/s390/net/netiucv.c
index 65ebee0..b6a6356 100644
--- a/drivers/s390/net/netiucv.c
+++ b/drivers/s390/net/netiucv.c
@@ -565,7 +565,7 @@
 	struct iucv_event ev;
 	int rc;
 
-	if (memcmp(iucvMagic, ipuser, sizeof(ipuser)))
+	if (memcmp(iucvMagic, ipuser, 16))
 		/* ipuser must match iucvMagic. */
 		return -EINVAL;
 	rc = -EINVAL;