diff --git a/apps/els_lsp/priv/code_navigation/src/diagnostics_xref.erl b/apps/els_lsp/priv/code_navigation/src/diagnostics_xref.erl
index 1e716ea2..b8be8f86 100644
--- a/apps/els_lsp/priv/code_navigation/src/diagnostics_xref.erl
+++ b/apps/els_lsp/priv/code_navigation/src/diagnostics_xref.erl
@@ -12,3 +12,6 @@ existing() ->
 dynamic_call(Foo, Bar) ->
   Foo:bar(),
   foo:Bar().
+
+not_exported() ->
+    code_navigation:function_c().
diff --git a/apps/els_lsp/src/els_code_action_provider.erl b/apps/els_lsp/src/els_code_action_provider.erl
index 2f0a4286..f48bd07b 100644
--- a/apps/els_lsp/src/els_code_action_provider.erl
+++ b/apps/els_lsp/src/els_code_action_provider.erl
@@ -62,6 +62,8 @@ make_code_actions(
             {"function (.*) undefined", fun els_code_actions:suggest_function/4},
             {"Cannot find definition for function (.*)", fun els_code_actions:suggest_function/4},
             {"Cannot find module (.*)", fun els_code_actions:suggest_module/4},
+            {"Function (.+):(.+) is not exported.",
+                fun els_code_actions:export_external_function/4},
             {"Unused file: (.*)", fun els_code_actions:remove_unused/4},
             {"Atom typo\\? Did you mean: (.*)", fun els_code_actions:fix_atom_typo/4},
             {"undefined callback function (.*) \\\(behaviour '(.*)'\\\)",
diff --git a/apps/els_lsp/src/els_code_actions.erl b/apps/els_lsp/src/els_code_actions.erl
index c4e8fb5d..9ae1e653 100644
--- a/apps/els_lsp/src/els_code_actions.erl
+++ b/apps/els_lsp/src/els_code_actions.erl
@@ -3,6 +3,7 @@
     extract_function/2,
     create_function/4,
     export_function/4,
+    export_external_function/4,
     fix_module_name/4,
     ignore_variable/4,
     remove_macro/4,
@@ -84,6 +85,32 @@ export_function(Uri, _Range, _Data, [UnusedFun]) ->
             ]
     end.
 
+-spec export_external_function(uri(), range(), binary(), [binary()]) -> [map()].
+export_external_function(_Uri, _Range, _Data, [ModBin, FABin]) ->
+    Mod = binary_to_atom(ModBin, utf8),
+    case els_utils:find_module(Mod) of
+        {ok, Uri} ->
+            {ok, Document} = els_utils:lookup_document(Uri),
+            case els_poi:sort(els_dt_document:pois(Document, [module, export])) of
+                [] ->
+                    [];
+                POIs ->
+                    #{range := #{to := {Line, _Col}}} = lists:last(POIs),
+                    Pos = {Line + 1, 1},
+                    [
+                        make_edit_action(
+                            Uri,
+                            <<"Export ", FABin/binary>>,
+                            ?CODE_ACTION_KIND_QUICKFIX,
+                            <<"-export([", FABin/binary, "]).\n">>,
+                            els_protocol:range(#{from => Pos, to => Pos})
+                        )
+                    ]
+            end;
+        {error, not_found} ->
+            []
+    end.
+
 -spec ignore_variable(uri(), range(), binary(), [binary()]) -> [map()].
 ignore_variable(Uri, Range, _Data, [UnusedVariable]) ->
     {ok, Document} = els_utils:lookup_document(Uri),
diff --git a/apps/els_lsp/src/els_crossref_diagnostics.erl b/apps/els_lsp/src/els_crossref_diagnostics.erl
index 5e6b03f5..dc1d60c3 100644
--- a/apps/els_lsp/src/els_crossref_diagnostics.erl
+++ b/apps/els_lsp/src/els_crossref_diagnostics.erl
@@ -18,6 +18,8 @@
     source/0
 ]).
 
+-type missing_reason() :: module | function | export.
+
 %%==============================================================================
 %% Includes
 %%==============================================================================
@@ -114,19 +116,23 @@ make_diagnostic({missing, Kind}, #{id := Id} = POI) ->
 make_diagnostic(true, _) ->
     [].
 
--spec range(module | function, els_poi:poi()) -> els_poi:poi_range().
+-spec range(missing_reason(), els_poi:poi()) -> els_poi:poi_range().
 range(module, #{data := #{mod_range := Range}}) ->
     Range;
 range(function, #{data := #{name_range := Range}}) ->
     Range;
+range(export, #{data := #{name_range := Range}}) ->
+    Range;
 range(_, #{range := Range}) ->
     Range.
 
--spec error_msg(module | function, els_poi:poi_id()) -> binary().
+-spec error_msg(missing_reason(), els_poi:poi_id()) -> binary().
 error_msg(module, {M, _F, _A}) ->
     els_utils:to_binary(io_lib:format("Cannot find module ~p", [M]));
 error_msg(function, Id) ->
-    els_utils:to_binary(io_lib:format("Cannot find definition for function ~s", [id_str(Id)])).
+    els_utils:to_binary(io_lib:format("Cannot find definition for function ~s", [id_str(Id)]));
+error_msg(export, Id) ->
+    els_utils:to_binary(io_lib:format("Function ~s is not exported.", [id_str(Id)])).
 
 -spec id_str(els_poi:poi_id()) -> string().
 id_str(Id) ->
@@ -136,7 +142,7 @@ id_str(Id) ->
     end.
 
 -spec has_definition(els_poi:poi(), els_dt_document:item(), _) ->
-    true | {missing, function | module}.
+    true | {missing, missing_reason()}.
 has_definition(#{data := #{imported := true}}, _Document, _Opts) ->
     %% Call to a bif
     true;
@@ -177,7 +183,9 @@ has_definition(
     case function_lookup(MFA) of
         true ->
             true;
-        false ->
+        {missing, export} ->
+            true;
+        {missing, function} ->
             case els_code_navigation:goto_definition(Uri, POI) of
                 {ok, _Defs} ->
                     true;
@@ -189,12 +197,14 @@ has_definition(#{id := {M, _F, _A} = MFA} = POI, _Document, _Opts) ->
     case function_lookup(MFA) of
         true ->
             true;
-        false ->
+        {missing, export} ->
+            {missing, export};
+        {missing, function} ->
             case els_utils:find_module(M) of
                 {ok, Uri} ->
                     case els_code_navigation:goto_definition(Uri, POI) of
                         {ok, _Defs} ->
-                            true;
+                            function_lookup(MFA);
                         {error, _Error} ->
                             {missing, function}
                     end;
@@ -205,13 +215,15 @@ has_definition(#{id := {M, _F, _A} = MFA} = POI, _Document, _Opts) ->
 has_definition(_POI, #{uri := _Uri}, _Opts) ->
     true.
 
--spec function_lookup(mfa()) -> boolean().
+-spec function_lookup(mfa()) -> true | {missing, missing_reason()}.
 function_lookup(MFA) ->
-    case els_db:lookup(els_dt_functions:name(), MFA) of
+    case els_dt_functions:lookup(MFA) of
         {ok, []} ->
-            false;
-        {ok, _} ->
-            true
+            {missing, function};
+        {ok, [#{is_exported := true}]} ->
+            true;
+        {ok, [#{is_exported := false}]} ->
+            {missing, export}
     end.
 
 -spec lager_definition(atom(), integer()) -> boolean().
diff --git a/apps/els_lsp/src/els_dt_functions.erl b/apps/els_lsp/src/els_dt_functions.erl
index 8b7b955e..5446be45 100644
--- a/apps/els_lsp/src/els_dt_functions.erl
+++ b/apps/els_lsp/src/els_dt_functions.erl
@@ -37,13 +37,15 @@
 
 -record(els_dt_functions, {
     mfa :: mfa() | '_' | {atom(), '_', '_'},
-    version :: version() | '_'
+    version :: version() | '_',
+    is_exported :: boolean() | '_'
 }).
 -type els_dt_functions() :: #els_dt_functions{}.
 -type version() :: null | integer().
 -type item() :: #{
     mfa := mfa(),
-    version := version()
+    version := version(),
+    is_exported := boolean()
 }.
 -export_type([item/0]).
 
@@ -65,21 +67,25 @@ opts() ->
 -spec from_item(item()) -> els_dt_functions().
 from_item(#{
     mfa := MFA,
-    version := Version
+    version := Version,
+    is_exported := IsExported
 }) ->
     #els_dt_functions{
         mfa = MFA,
-        version = Version
+        version = Version,
+        is_exported = IsExported
     }.
 
 -spec to_item(els_dt_functions()) -> item().
 to_item(#els_dt_functions{
     mfa = MFA,
-    version = Version
+    version = Version,
+    is_exported = IsExported
 }) ->
     #{
         mfa => MFA,
-        version => Version
+        version => Version,
+        is_exported => IsExported
     }.
 
 -spec insert(item()) -> ok | {error, any()}.
@@ -96,8 +102,7 @@ versioned_insert(#{mfa := MFA, version := Version} = Map) ->
     els_db:conditional_write(name(), MFA, Record, Condition).
 
 -spec lookup(mfa()) -> {ok, [item()]}.
-lookup({M, _F, _A} = MFA) ->
-    {ok, _Uris} = els_utils:find_modules(M),
+lookup(MFA) ->
     {ok, Items} = els_db:lookup(name(), MFA),
     {ok, [to_item(Item) || Item <- Items]}.
 
diff --git a/apps/els_lsp/src/els_indexing.erl b/apps/els_lsp/src/els_indexing.erl
index 99eca4ee..773737d1 100644
--- a/apps/els_lsp/src/els_indexing.erl
+++ b/apps/els_lsp/src/els_indexing.erl
@@ -137,14 +137,17 @@ index_signature(M, Text, #{id := {F, A}, range := Range, data := #{args := Args}
 -spec index_functions(atom(), uri(), [els_poi:poi()], version()) -> ok.
 index_functions(M, Uri, POIs, Version) ->
     ok = els_dt_functions:versioned_delete_by_uri(Uri, Version),
-    [index_function(M, POI, Version) || #{kind := function} = POI <- POIs],
+    Exports = [{F, A} || #{id := {F, A}, kind := export_entry} <- POIs],
+    [index_function(M, POI, Exports, Version) || #{kind := function} = POI <- POIs],
     ok.
 
--spec index_function(atom(), els_poi:poi(), version()) -> ok.
-index_function(M, #{id := {F, A}}, Version) ->
+-spec index_function(atom(), els_poi:poi(), els_poi:poi_id(), version()) -> ok.
+index_function(M, #{id := {F, A}}, Exports, Version) ->
+    IsExported = lists:member({F, A}, Exports),
     els_dt_functions:versioned_insert(#{
         mfa => {M, F, A},
-        version => Version
+        version => Version,
+        is_exported => IsExported
     }).
 
 -spec index_references(atom(), uri(), [els_poi:poi()], version()) -> ok.
diff --git a/apps/els_lsp/test/els_code_action_SUITE.erl b/apps/els_lsp/test/els_code_action_SUITE.erl
index 1e1a51bd..68f1f2f3 100644
--- a/apps/els_lsp/test/els_code_action_SUITE.erl
+++ b/apps/els_lsp/test/els_code_action_SUITE.erl
@@ -14,6 +14,7 @@
 -export([
     add_underscore_to_unused_var/1,
     export_unused_function/1,
+    export_external_function/1,
     suggest_variable/1,
     fix_module_name/1,
     remove_unused_macro/1,
@@ -158,6 +159,54 @@ export_unused_function(Config) ->
     ?assertEqual(Expected, Result),
     ok.
 
+-spec export_external_function(config()) -> ok.
+export_external_function(Config) ->
+    Uri = ?config(code_navigation_uri, Config),
+    %% Don't care
+    Range = els_protocol:range(#{
+        from => {1, 1},
+        to => {1, 2}
+    }),
+    Diag = #{
+        message => <<"Function code_action:function_c/0 is not exported.">>,
+        range => Range,
+        severity => 2,
+        source => <<"CrossRef">>
+    },
+    #{result := Result} = els_client:document_codeaction(Uri, Range, [Diag]),
+    TargetUri = ?config(code_action_uri, Config),
+    Expected =
+        [
+            #{
+                edit => #{
+                    changes =>
+                        #{
+                            binary_to_atom(TargetUri, utf8) =>
+                                [
+                                    #{
+                                        range =>
+                                            #{
+                                                'end' => #{
+                                                    character => 0,
+                                                    line => ?COMMENTS_LINES + 3
+                                                },
+                                                start => #{
+                                                    character => 0,
+                                                    line => ?COMMENTS_LINES + 3
+                                                }
+                                            },
+                                        newText => <<"-export([function_c/0]).\n">>
+                                    }
+                                ]
+                        }
+                },
+                kind => <<"quickfix">>,
+                title => <<"Export function_c/0">>
+            }
+        ],
+    ?assertEqual(Expected, Result),
+    ok.
+
 -spec suggest_variable(config()) -> ok.
 suggest_variable(Config) ->
     Uri = ?config(code_action_uri, Config),
diff --git a/apps/els_lsp/test/els_diagnostics_SUITE.erl b/apps/els_lsp/test/els_diagnostics_SUITE.erl
index 64f44925..070062cd 100644
--- a/apps/els_lsp/test/els_diagnostics_SUITE.erl
+++ b/apps/els_lsp/test/els_diagnostics_SUITE.erl
@@ -786,6 +786,12 @@ crossref(_Config) ->
             #{
                 message => <<"Cannot find definition for function lists:map/3">>,
                 range => {{5, 8}, {5, 11}}
+            },
+
+            #{
+                message =>
+                    <<"Function code_navigation:function_c/0 is not exported.">>,
+                range => {{16, 20}, {16, 30}}
             }
         ],
     Warnings = [],
@@ -802,6 +808,11 @@ crossref_compiler_enabled(_Config) ->
             #{
                 message => <<"Cannot find definition for function lists:map/3">>,
                 range => {{5, 8}, {5, 11}}
+            },
+            #{
+                message =>
+                    <<"Function code_navigation:function_c/0 is not exported.">>,
+                range => {{16, 20}, {16, 30}}
             }
         ],
     Warnings = [],