diff --git a/lightningd/peer_control.c b/lightningd/peer_control.c
index cdbe297fe..634073004 100644
--- a/lightningd/peer_control.c
+++ b/lightningd/peer_control.c
@@ -23,6 +23,7 @@
 #include <lightningd/channel/gen_channel_wire.h>
 #include <lightningd/closing/gen_closing_wire.h>
 #include <lightningd/commit_tx.h>
+#include <lightningd/dev_disconnect.h>
 #include <lightningd/funding_tx.h>
 #include <lightningd/gen_peer_state_names.h>
 #include <lightningd/gossip/gen_gossip_wire.h>
@@ -151,6 +152,11 @@ void peer_fail_transient(struct peer *peer, const char *fmt, ...)
 	logv_add(peer->log, fmt, ap);
 	va_end(ap);
 
+	if (dev_disconnect_permanent(peer->ld)) {
+		peer_internal_error(peer, "dev_disconnect permfail");
+		return;
+	}
+
 	peer->owner = NULL;
 
 	/* If we haven't reached awaiting locked, we don't need to reconnect */
diff --git a/lightningd/subd.c b/lightningd/subd.c
index e52a03006..0fe43282e 100644
--- a/lightningd/subd.c
+++ b/lightningd/subd.c
@@ -1,5 +1,6 @@
 #include <ccan/io/fdpass/fdpass.h>
 #include <ccan/io/io.h>
+#include <ccan/mem/mem.h>
 #include <ccan/noerr/noerr.h>
 #include <ccan/take/take.h>
 #include <ccan/tal/path/path.h>
@@ -510,3 +511,20 @@ char *opt_subd_dev_disconnect(const char *optarg, struct lightningd *ld)
 			       optarg, strerror(errno));
 	return NULL;
 }
+
+/* If test specified that this disconnection should cause permanent failure */
+bool dev_disconnect_permanent(struct lightningd *ld)
+{
+	char permfail[strlen("PERMFAIL")];
+	int r;
+
+	if (ld->dev_disconnect_fd == -1)
+		return false;
+
+	r = read(ld->dev_disconnect_fd, permfail, sizeof(permfail));
+	if (r < 0)
+		fatal("Reading dev_disconnect file: %s", strerror(errno));
+	lseek(ld->dev_disconnect_fd, -r, SEEK_CUR);
+
+	return memeq(permfail, r, "permfail", strlen("permfail"));
+}
diff --git a/lightningd/subd.h b/lightningd/subd.h
index 2f12ce76b..3f6705c43 100644
--- a/lightningd/subd.h
+++ b/lightningd/subd.h
@@ -135,4 +135,6 @@ void subd_shutdown(struct subd *subd, unsigned int seconds);
 
 char *opt_subd_debug(const char *optarg, struct lightningd *ld);
 char *opt_subd_dev_disconnect(const char *optarg, struct lightningd *ld);
+
+bool dev_disconnect_permanent(struct lightningd *ld);
 #endif /* LIGHTNING_LIGHTNINGD_SUBD_H */