diff --git a/drivers/net/dm9k.c b/drivers/net/dm9k.c
index 40a7c67..983edd4 100644
--- a/drivers/net/dm9k.c
+++ b/drivers/net/dm9k.c
@@ -299,6 +299,8 @@
 	case IORESOURCE_MEM_32BIT:
 		rc = dm9k_read_packet_status_32(port, status);
 		break;
+	default:
+		rc = -EINVAL;
 	}
 
 	return rc;