diff --git a/openbsc/src/libbsc/bsc_vty.c b/openbsc/src/libbsc/bsc_vty.c
index 2a4d0b3..8bfbb24 100644
--- a/openbsc/src/libbsc/bsc_vty.c
+++ b/openbsc/src/libbsc/bsc_vty.c
@@ -890,7 +890,7 @@
 		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);