diff --git a/apps/emqx/src/emqx_schema.erl b/apps/emqx/src/emqx_schema.erl
index 7d1e39510..812e52f9b 100644
--- a/apps/emqx/src/emqx_schema.erl
+++ b/apps/emqx/src/emqx_schema.erl
@@ -342,7 +342,7 @@ mqtt_listener() ->
     ].
 
 base_listener() ->
-    [ {"bind", t(union(ip_port(), integer()))}
+    [ {"bind", hoconsc:t(union(ip_port(), integer()), #{nullable => false})}
     , {"acceptors", t(integer(), undefined, 16)}
     , {"max_connections", maybe_infinity(integer(), infinity)}
     , {"mountpoint", t(binary(), undefined, <<>>)}