diff --git a/openbsc/src/libmsc/vty_interface_layer3.c b/openbsc/src/libmsc/vty_interface_layer3.c
index 68d9c44..558db5e 100644
--- a/openbsc/src/libmsc/vty_interface_layer3.c
+++ b/openbsc/src/libmsc/vty_interface_layer3.c
@@ -548,6 +548,13 @@
 		return CMD_WARNING;
 	}
 
+	if (strlen(name) > sizeof(subscr->name)-1) {
+		vty_out(vty,
+			"%% NAME is too long, max. %d characters are allowed%s",
+			sizeof(subscr->name)-1, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
 	strncpy(subscr->name, name, sizeof(subscr->name));
 	talloc_free(name);
 	db_sync_subscriber(subscr);
@@ -574,6 +581,13 @@
 		return CMD_WARNING;
 	}
 
+	if (strlen(ext) > sizeof(subscr->extension)-1) {
+		vty_out(vty,
+			"%% EXTENSION is too long, max. %d characters are allowed%s",
+			sizeof(subscr->extension)-1, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
 	strncpy(subscr->extension, ext, sizeof(subscr->extension));
 	db_sync_subscriber(subscr);