diff --git a/apps/efka/src/tcp_channel.erl b/apps/efka/src/tcp_channel.erl
index af76c28..bbf9e68 100644
--- a/apps/efka/src/tcp_channel.erl
+++ b/apps/efka/src/tcp_channel.erl
@@ -57,16 +57,19 @@
 %%% API
 %%%===================================================================
 
+-spec push_param(ChannelPid :: pid(), Params :: binary()) -> {ok, Ref :: reference()}.
 push_param(ChannelPid, Params) when is_pid(ChannelPid), is_binary(Params) ->
     Ref = make_ref(),
     gen_server:cast(ChannelPid, {push_param, Ref, self(), Params}),
     {ok, Ref}.
 
+-spec push_metric(ChannelPid :: pid(), Metrics :: binary()) -> {ok, Ref :: reference()}.
 push_metric(ChannelPid, Metrics) when is_pid(ChannelPid), is_binary(Metrics) ->
     Ref = make_ref(),
     gen_server:cast(ChannelPid, {push_metric, Ref, self(), Metrics}),
     {ok, Ref}.
 
+-spec poll(ChannelPid :: pid(), Command :: binary()) -> {ok, Ref :: reference()}.
 poll(ChannelPid, Command) when is_pid(ChannelPid), is_binary(Command) ->
     Ref = make_ref(),
     gen_server:cast(ChannelPid, {poll, Ref, self(), Command}),