diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index b29dacf..e6e1cbe 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -1781,10 +1781,13 @@
 			return -EFAULT;
 		i += len;
 		mutex_lock(&pktgen_thread_lock);
-		pktgen_add_device(t, f);
+		ret = pktgen_add_device(t, f);
 		mutex_unlock(&pktgen_thread_lock);
-		ret = count;
-		sprintf(pg_result, "OK: add_device=%s", f);
+		if (!ret) {
+			ret = count;
+			sprintf(pg_result, "OK: add_device=%s", f);
+		} else
+			sprintf(pg_result, "ERROR: can not add device %s", f);
 		goto out;
 	}