diff --git a/src/hocon_schema.erl b/src/hocon_schema.erl
index b61ca13..953f0e9 100644
--- a/src/hocon_schema.erl
+++ b/src/hocon_schema.erl
@@ -348,11 +348,25 @@ find_structs_per_type(Schema, ?UNION(Types0, _), Acc, Stack, TStack, Opts) ->
         Acc,
         Types
     );
-find_structs_per_type(Schema, ?MAP(Name, Type), Acc, Stack, TStack, Opts) ->
-    find_structs_per_type(Schema, Type, Acc, ["$" ++ str(Name) | Stack], TStack, Opts);
+find_structs_per_type(Schema, ?MAP(NameType, Type), Acc, Stack, TStack, Opts) ->
+    find_structs_per_type(
+        Schema, Type, Acc, ["$" ++ str(get_map_key_type_name(NameType)) | Stack], TStack, Opts
+    );
 find_structs_per_type(_Schema, _Type, Acc, _Stack, _TStack, _Opts) ->
     Acc.
 
+get_map_key_type_name(Fun) when is_function(Fun, 1) ->
+    case Fun(name) of
+        undefined ->
+            name;
+        Name ->
+            Name
+    end;
+get_map_key_type_name(Map) when is_map(Map) ->
+    maps:get(name, Map, name);
+get_map_key_type_name(Name) ->
+    Name.
+
 find_ref(Schema, Name, Acc, Stack, TStack, Opts) ->
     Namespace = namespace(Schema),
     Key = {Namespace, Schema, Name},
@@ -488,10 +502,10 @@ fmt_type(_Ns, ?ENUM(Symbols)) ->
     };
 fmt_type(Ns, ?LAZY(T)) ->
     fmt_type(Ns, T);
-fmt_type(Ns, ?MAP(Name, T)) ->
+fmt_type(Ns, ?MAP(NameType, T)) ->
     #{
         kind => map,
-        name => bin(Name),
+        name => bin(get_map_key_type_name(NameType)),
         values => fmt_type(Ns, T)
     };
 fmt_type(_Ns, Type) when ?IS_TYPEREFL(Type) ->
diff --git a/src/hocon_tconf.erl b/src/hocon_tconf.erl
index 04a3a38..8803b33 100644
--- a/src/hocon_tconf.erl
+++ b/src/hocon_tconf.erl
@@ -551,15 +551,15 @@ map_field_maybe_convert(Type, Schema, Value0, Opts, Converter) ->
             }
     end.
 
-map_field(?MAP(_Name, Type), FieldSchema, Value, Opts) ->
+map_field(?MAP(NameType, Type), FieldSchema, Value, Opts) ->
     %% map type always has string keys
     Keys = maps_keys(unbox(Opts, Value)),
     case [str(K) || K <- Keys] of
         [] ->
             {[], Value};
         FieldNames ->
-            case get_invalid_name(FieldNames, Opts) of
-                [] ->
+            case check_map_key_name(NameType, FieldNames) of
+                ok ->
                     %% All objects in this map should share the same schema.
                     NewSc = hocon_schema:override(
                         FieldSchema,
@@ -568,13 +568,10 @@ map_field(?MAP(_Name, Type), FieldSchema, Value, Opts) ->
                     NewFields = [{FieldName, NewSc} || FieldName <- FieldNames],
                     %% start over
                     do_map(NewFields, Value, Opts, NewSc);
-                InvalidNames ->
+                {error, Meta} ->
                     Context =
-                        #{
-                            reason => invalid_map_key,
-                            expected_data_type => ?MAP_KEY_RE,
-                            hint => "map keys must have less than 255 bytes",
-                            got => InvalidNames
+                        Meta#{
+                            reason => invalid_map_key
                         },
                     {validation_errs(Opts, Context), Value}
             end
@@ -1307,26 +1304,53 @@ check_index_seq(I, [{Index, V} | Rest], Acc) ->
             }}
     end.
 
-get_invalid_name(Names, Opts) ->
-    AtomKey =
-        case maps:get(atom_key, Opts, false) of
-            true -> true;
-            {true, unsafe} -> true;
-            _ -> false
-        end,
-    lists:filter(
-        fun(F) ->
-            DoesNotMatchRE =
-                try
-                    nomatch =:= re:run(F, ?MAP_KEY_RE)
-                catch
-                    _:_ -> false
-                end,
-            TooLong = AtomKey andalso string:length(F) > 255,
-            DoesNotMatchRE orelse TooLong
-        end,
-        Names
-    ).
+check_map_key_name(NameType, Names) ->
+    Validator = get_map_key_name_validator(NameType),
+    check_map_key_name2(Validator, Names).
+
+check_map_key_name2(Validator, [Name | T]) ->
+    try Validator(Name) of
+        ok ->
+            check_map_key_name2(Validator, T);
+        {error, _Meta} = Error ->
+            Error
+    catch
+        _:Reason ->
+            {error, #{name => Name, message => Reason}}
+    end;
+check_map_key_name2(_Validator, []) ->
+    ok.
+
+get_map_key_name_validator(Fun) when is_function(Fun, 1) ->
+    case Fun(validator) of
+        undefined ->
+            fun default_map_key_name_validator/1;
+        Validator ->
+            Validator
+    end;
+get_map_key_name_validator(Meta) when is_map(Meta) ->
+    maps:get(validator, Meta, fun default_map_key_name_validator/1);
+get_map_key_name_validator(_NameType) ->
+    fun default_map_key_name_validator/1.
+
+default_map_key_name_validator(Name) ->
+    case re:run(Name, ?MAP_KEY_RE) of
+        nomatch ->
+            {error, #{
+                expected_data_type => ?MAP_KEY_RE,
+                got => Name
+            }};
+        _ ->
+            case string:length(Name) > 255 of
+                true ->
+                    {error, #{
+                        hint => "map keys must have less than 255 bytes",
+                        got => Name
+                    }};
+                _ ->
+                    ok
+            end
+    end.
 
 fmt_field_names(Names) ->
     do_fmt_field_names(lists:sort(lists:map(fun str/1, Names))).
diff --git a/test/hocon_schema_example_tests.erl b/test/hocon_schema_example_tests.erl
index 854cbc4..045406e 100644
--- a/test/hocon_schema_example_tests.erl
+++ b/test/hocon_schema_example_tests.erl
@@ -60,6 +60,8 @@ fields("example") ->
             )},
         {map_key1, ?HOCON(hoconsc:map(map_name1, ?REF("map_name")), #{example1s => MapExample})},
         {map_key2, ?HOCON(hoconsc:map(map_name2, ?REF("map_name")), #{})},
+        {map_key3, ?HOCON(hoconsc:map(fun(name) -> map_name3 end, ?REF("map_name")), #{})},
+        {map_key4, ?HOCON(hoconsc:map(#{name => map_key4}, ?REF("map_name")), #{})},
         {union_key, ?HOCON(Union, #{examples => UnionExample})},
         {union_key2, Union},
         {array_key, hoconsc:array(?R_REF(emqx_schema, "mcast"))},
diff --git a/test/hocon_tconf_tests.erl b/test/hocon_tconf_tests.erl
index 31a95ac..6372074 100644
--- a/test/hocon_tconf_tests.erl
+++ b/test/hocon_tconf_tests.erl
@@ -389,27 +389,66 @@ mapping_test_() ->
         )
     ].
 
-map_key_test() ->
-    Sc = #{roots => [{"val", hoconsc:map(key, string())}]},
-    GoodConf = "val = {good_GOOD = value}",
-    {ok, GoodMap} = hocon:binary(GoodConf, #{format => map}),
-    ?assertEqual(
-        #{<<"val">> => #{<<"good_GOOD">> => "value"}},
-        hocon_tconf:check_plain(Sc, GoodMap, #{apply_override_envs => false})
-    ),
+map_key_test_() ->
+    Checker = fun(KeyType, GoodConf, GoodResult, BadConfs) ->
+        Sc = #{roots => [{"val", hoconsc:map(KeyType, string())}]},
+        {ok, GoodMap} = hocon:binary(GoodConf, #{format => map}),
+        ?assertEqual(
+            GoodResult,
+            hocon_tconf:check_plain(Sc, GoodMap, #{apply_override_envs => false})
+        ),
 
-    BadConfs = ["val = {\"_bad\" = value}", "val = {\"bad_-n\" = value}"],
-    lists:foreach(
-        fun(BadConf) ->
-            {ok, BadMap} = hocon:binary(BadConf, #{format => map}),
-            ?GEN_VALIDATION_ERR(
-                #{path := "val", reason := invalid_map_key},
-                hocon_tconf:check_plain(Sc, BadMap, #{apply_override_envs => false})
+        lists:foreach(
+            fun(BadConf) ->
+                {ok, BadMap} = hocon:binary(BadConf, #{format => map}),
+                ?GEN_VALIDATION_ERR(
+                    #{path := "val", reason := invalid_map_key},
+                    hocon_tconf:check_plain(Sc, BadMap, #{apply_override_envs => false})
+                )
+            end,
+            BadConfs
+        )
+    end,
+    Normal =
+        {"map_key_test", fun() ->
+            Checker(
+                key,
+                "val = {good_GOOD = value}",
+                #{<<"val">> => #{<<"good_GOOD">> => "value"}},
+                ["val = {\"_bad\" = value}", "val = {\"bad_-n\" = value}"]
             )
-        end,
-        BadConfs
-    ),
-    ok.
+        end},
+    Validator = fun(Name) ->
+        case re:run(Name, "[a-z]") of
+            nomatch ->
+                {error, #{}};
+            _ ->
+                ok
+        end
+    end,
+    Fun =
+        {"fun_map_key_test", fun() ->
+            Checker(
+                fun(validator) ->
+                    Validator
+                end,
+                "val = {good = value}",
+                #{<<"val">> => #{<<"good">> => "value"}},
+                ["val = {Bad = value}", "val = {bad1 = value}"]
+            )
+        end},
+    Struct =
+        {"structal_map_key_test", fun() ->
+            Checker(
+                #{
+                    validator => Validator
+                },
+                "val = {good = value}",
+                #{<<"val">> => #{<<"good">> => "value"}},
+                ["val = {Bad = value}", "val = {bad1 = value}"]
+            )
+        end},
+    [Normal, Fun, Struct].
 
 generate_compatibility_test() ->
     Conf = [
@@ -2466,8 +2505,7 @@ map_atom_keys_test_() ->
                 ?assertThrow(
                     {_, [
                         #{
-                            kind := validation_error,
-                            got := [BadKeyStr],
+                            got := BadKeyStr,
                             reason := invalid_map_key
                         }
                     ]},
@@ -2486,8 +2524,7 @@ map_atom_keys_test_() ->
                 ?assertThrow(
                     {_, [
                         #{
-                            kind := validation_error,
-                            got := [BadKeyStr],
+                            got := BadKeyStr,
                             reason := invalid_map_key
                         }
                     ]},
@@ -2503,8 +2540,13 @@ map_atom_keys_test_() ->
                 BadKeyStr = lists:duplicate(256, $a),
                 BadKey = list_to_binary(BadKeyStr),
                 BadMap = #{<<"root">> => #{BadKey => #{<<"foo">> => #{}}}},
-                ?assertMatch(
-                    #{<<"root">> := #{BadKey := _}},
+                ?assertThrow(
+                    {_, [
+                        #{
+                            got := BadKeyStr,
+                            reason := invalid_map_key
+                        }
+                    ]},
                     hocon_tconf:check_plain(
                         Sc,
                         BadMap,