diff --git a/openbsc/src/libbsc/bsc_vty.c b/openbsc/src/libbsc/bsc_vty.c
index 2a4d0b3fb..8bfbb240d 100644
--- a/openbsc/src/libbsc/bsc_vty.c
+++ b/openbsc/src/libbsc/bsc_vty.c
@@ -890,7 +890,7 @@ static void subscr_dump_vty(struct vty *vty, struct gsm_subscriber *subscr)
 		subscr->authorized, VTY_NEWLINE);
 	if (strlen(subscr->name))
 		vty_out(vty, "    Name: '%s'%s", subscr->name, VTY_NEWLINE);
-	if (subscr->extension)
+	if (strlen(subscr->extension))
 		vty_out(vty, "    Extension: %s%s", subscr->extension,
 			VTY_NEWLINE);
 	vty_out(vty, "    IMSI: %s%s", subscr->imsi, VTY_NEWLINE);
diff --git a/openbsc/src/libmsc/vty_interface_layer3.c b/openbsc/src/libmsc/vty_interface_layer3.c
index 923cba062..5b727ef4c 100644
--- a/openbsc/src/libmsc/vty_interface_layer3.c
+++ b/openbsc/src/libmsc/vty_interface_layer3.c
@@ -62,7 +62,7 @@ static void subscr_dump_full_vty(struct vty *vty, struct gsm_subscriber *subscr,
 		subscr->authorized, VTY_NEWLINE);
 	if (strlen(subscr->name))
 		vty_out(vty, "    Name: '%s'%s", subscr->name, VTY_NEWLINE);
-	if (subscr->extension)
+	if (strlen(subscr->extension))
 		vty_out(vty, "    Extension: %s%s", subscr->extension,
 			VTY_NEWLINE);
 	vty_out(vty, "    LAC: %d/0x%x%s",