diff --git a/apps/els_lsp/src/els_code_actions.erl b/apps/els_lsp/src/els_code_actions.erl
index 96c7d406..c4e8fb5d 100644
--- a/apps/els_lsp/src/els_code_actions.erl
+++ b/apps/els_lsp/src/els_code_actions.erl
@@ -191,9 +191,8 @@ add_include_lib_record(Uri, Range, _Data, [Record]) ->
 -spec add_include_file(uri(), range(), els_poi:poi_kind(), atom(), els_poi:poi_id()) -> [map()].
 add_include_file(Uri, Range, Kind, Name, Id) ->
     %% TODO: Add support for -include() also
-    %% TODO: Doesn't work for OTP headers
     CandidateUris =
-        els_dt_document:find_candidates(Name, 'header'),
+        els_dt_document:find_candidates_with_otp(Name, 'header'),
     Uris = [
         CandidateUri
      || CandidateUri <- CandidateUris,
diff --git a/apps/els_lsp/src/els_completion_provider.erl b/apps/els_lsp/src/els_completion_provider.erl
index 68cb5a57..bce853e0 100644
--- a/apps/els_lsp/src/els_completion_provider.erl
+++ b/apps/els_lsp/src/els_completion_provider.erl
@@ -946,20 +946,14 @@ item_kind_module(Module) ->
 
 -spec behaviour_modules(list()) -> [atom()].
 behaviour_modules(Begin) ->
-    OtpBehaviours = [
-        gen_event,
-        gen_server,
-        gen_statem,
-        supervisor
-    ],
-    Candidates = els_dt_document:find_candidates(callback),
+    Candidates = els_dt_document:find_candidates_with_otp(callback, 'module'),
     Behaviours = [
         els_uri:module(Uri)
      || Uri <- Candidates,
         lists:prefix(Begin, atom_to_list(els_uri:module(Uri))),
         is_behaviour(Uri)
     ],
-    OtpBehaviours ++ Behaviours.
+    Behaviours.
 
 -spec is_behaviour(uri()) -> boolean().
 is_behaviour(Uri) ->
diff --git a/apps/els_lsp/src/els_dt_document.erl b/apps/els_lsp/src/els_dt_document.erl
index 14c8fb9d..aee88268 100644
--- a/apps/els_lsp/src/els_dt_document.erl
+++ b/apps/els_lsp/src/els_dt_document.erl
@@ -39,6 +39,7 @@
     wrapping_functions/3,
     find_candidates/1,
     find_candidates/2,
+    find_candidates_with_otp/2,
     get_words/1
 ]).
 
@@ -66,7 +67,7 @@
     kind :: kind() | '_',
     text :: binary() | '_',
     pois :: [els_poi:poi()] | '_' | ondemand,
-    source :: source() | '$2',
+    source :: source() | '_' | '$2',
     words :: sets:set() | '_' | '$3',
     version :: version() | '_'
 }).
@@ -300,6 +301,35 @@ find_candidates(Pattern, Kind) ->
     end,
     lists:filtermap(Fun, All).
 
+-spec find_candidates_with_otp(atom() | string(), module | header | '_') -> [uri()].
+find_candidates_with_otp(Pattern, Kind) ->
+    %% ets:fun2ms(fun(#els_dt_document{source = Source, uri = Uri, words = Words})
+    %% when Source =/= otp -> {Uri, Words} end).
+    MS = [
+        {
+            #els_dt_document{
+                uri = '$1',
+                id = '_',
+                kind = Kind,
+                text = '_',
+                pois = '_',
+                source = '_',
+                words = '$3',
+                version = '_'
+            },
+            [],
+            [{{'$1', '$3'}}]
+        }
+    ],
+    All = ets:select(name(), MS),
+    Fun = fun({Uri, Words}) ->
+        case sets:is_element(Pattern, Words) of
+            true -> {true, Uri};
+            false -> false
+        end
+    end,
+    lists:filtermap(Fun, All).
+
 -spec get_words(binary()) -> sets:set().
 get_words(Text) ->
     case erl_scan:string(els_utils:to_list(Text)) of
diff --git a/apps/els_lsp/test/els_completion_SUITE.erl b/apps/els_lsp/test/els_completion_SUITE.erl
index 7c7535a0..fa056fc9 100644
--- a/apps/els_lsp/test/els_completion_SUITE.erl
+++ b/apps/els_lsp/test/els_completion_SUITE.erl
@@ -311,26 +311,6 @@ attribute_behaviour(Config) ->
     Uri = ?config(completion_attributes_uri, Config),
     TriggerKindInvoked = ?COMPLETION_TRIGGER_KIND_INVOKED,
     Expected = [
-        #{
-            insertTextFormat => ?INSERT_TEXT_FORMAT_PLAIN_TEXT,
-            kind => ?COMPLETION_ITEM_KIND_MODULE,
-            label => <<"gen_event">>
-        },
-        #{
-            insertTextFormat => ?INSERT_TEXT_FORMAT_PLAIN_TEXT,
-            kind => ?COMPLETION_ITEM_KIND_MODULE,
-            label => <<"gen_server">>
-        },
-        #{
-            insertTextFormat => ?INSERT_TEXT_FORMAT_PLAIN_TEXT,
-            kind => ?COMPLETION_ITEM_KIND_MODULE,
-            label => <<"gen_statem">>
-        },
-        #{
-            insertTextFormat => ?INSERT_TEXT_FORMAT_PLAIN_TEXT,
-            kind => ?COMPLETION_ITEM_KIND_MODULE,
-            label => <<"supervisor">>
-        },
         #{
             insertTextFormat => ?INSERT_TEXT_FORMAT_PLAIN_TEXT,
             kind => ?COMPLETION_ITEM_KIND_MODULE,