diff --git a/drivers/isdn/mISDN/dsp_core.c b/drivers/isdn/mISDN/dsp_core.c
index 22b720e..77025f5 100644
--- a/drivers/isdn/mISDN/dsp_core.c
+++ b/drivers/isdn/mISDN/dsp_core.c
@@ -288,8 +288,10 @@
 	u8 *data;
 	int len;
 
-	if (skb->len < sizeof(int))
+	if (skb->len < sizeof(int)) {
 		printk(KERN_ERR "%s: PH_CONTROL message too short\n", __func__);
+		return -EINVAL;
+	}
 	cont = *((int *)skb->data);
 	len = skb->len - sizeof(int);
 	data = skb->data + sizeof(int);