diff --git a/apps/emqx/src/emqx_schema.erl b/apps/emqx/src/emqx_schema.erl
index 4f4c7e481..1a617c6c8 100644
--- a/apps/emqx/src/emqx_schema.erl
+++ b/apps/emqx/src/emqx_schema.erl
@@ -48,7 +48,7 @@
 -type wordsize() :: bytesize().
 -type percent() :: float().
 -type file() :: string().
--type comma_separated_list() :: list().
+-type comma_separated_list() :: list(string()).
 -type comma_separated_binary() :: [binary()].
 -type comma_separated_atoms() :: [atom()].
 -type ip_port() :: tuple() | integer().
diff --git a/apps/emqx_gateway/src/emqx_gateway_schema.erl b/apps/emqx_gateway/src/emqx_gateway_schema.erl
index e58e552e2..ed149d1f5 100644
--- a/apps/emqx_gateway/src/emqx_gateway_schema.erl
+++ b/apps/emqx_gateway/src/emqx_gateway_schema.erl
@@ -32,19 +32,16 @@
 -type duration() :: non_neg_integer().
 -type duration_s() :: non_neg_integer().
 -type bytesize() :: pos_integer().
--type comma_separated_list() :: list().
 
 -typerefl_from_string({ip_port/0, emqx_schema, to_ip_port}).
 -typerefl_from_string({duration/0, emqx_schema, to_duration}).
 -typerefl_from_string({duration_s/0, emqx_schema, to_duration_s}).
 -typerefl_from_string({bytesize/0, emqx_schema, to_bytesize}).
--typerefl_from_string({comma_separated_list/0, emqx_schema, to_comma_separated_list}).
 
 -reflect_type([
     duration/0,
     duration_s/0,
     bytesize/0,
-    comma_separated_list/0,
     ip_port/0
 ]).
 -elvis([{elvis_style, dont_repeat_yourself, disable}]).