Index: uspace/lib/drv/generic/driver.c
===================================================================
--- uspace/lib/drv/generic/driver.c	(revision 151293d079b1d485097c6183782ecfa92c55e6cd)
+++ uspace/lib/drv/generic/driver.c	(revision 48141f0eae5158f60e7939fae200cd04453841d1)
@@ -405,5 +405,6 @@
 				/* The interface has not such method */
 				printf("%s: driver_connection_gen error - "
-				    "invalid interface method (%d).\n",
+				    "invalid interface method "
+				    "(index %" PRIun ").\n",
 				    driver->name, iface_method_idx);
 				async_answer_0(callid, ENOTSUP);