--- sbin/ggate/ggatec/ggatec.c.orig	2016-04-13 00:49:31.168895372 +0900
+++ sbin/ggate/ggatec/ggatec.c	2016-10-14 19:56:04.816030000 +0900
@@ -142,6 +142,10 @@
 		case BIO_WRITE:
 			hdr.gh_cmd = GGATE_CMD_WRITE;
 			break;
+		default:
+			ggio.gctl_error = EOPNOTSUPP;
+			g_gate_ioctl(G_GATE_CMD_DONE, &ggio);
+			continue;
 		}
 		hdr.gh_seq = ggio.gctl_seq;
 		hdr.gh_offset = ggio.gctl_offset;