diff --git a/src/gmmpp_msgs.erl b/src/gmmpp_msgs.erl
index d2dfe20..7680144 100644
--- a/src/gmmpp_msgs.erl
+++ b/src/gmmpp_msgs.erl
@@ -149,14 +149,14 @@ decode(MsgBin, ?PROTOCOL_JSON, Vsn) ->
 encode_msg(Msg0, ?PROTOCOL_JSON, Vsn) ->
     Msg = validate(Msg0, Vsn),
     [{Method, Args}] = maps:to_list(Msg),
-    json:encode(#{ <<"jsonrpc">> => <<"2.0">>
+    json_encode(#{ <<"jsonrpc">> => <<"2.0">>
                  , <<"method">>  => Method
                  , <<"args">>    => Args }).
 
 encode_request(Req0, Id, ?PROTOCOL_JSON, Vsn) ->
     Req = validate(Req0, Vsn),
     [{Method, Args}] = maps:to_list(Req),
-    json:encode(#{ <<"jsonrpc">> => <<"2.0">>
+    json_encode(#{ <<"jsonrpc">> => <<"2.0">>
                  , <<"id">>      => Id
                  , <<"method">>  => Method
                  , <<"args">>    => Args }).
@@ -166,7 +166,7 @@ encode_reply(Reply0, Id, ?PROTOCOL_JSON, Vsn) when is_map(Reply0) ->
     Msg = #{ <<"jsonrpc">> => <<"2.0">>
            , <<"id">>      => Id
            , <<"result">>  => Reply },
-    json:encode(Msg);
+    json_encode(Msg);
 encode_reply(Reply, Id, ?PROTOCOL_JSON, _Vsn) ->
     Msg = case Reply of
               {error, Reason} ->
@@ -179,7 +179,10 @@ encode_reply(Reply, Id, ?PROTOCOL_JSON, _Vsn) ->
                    , <<"id">>      => Id
                    , <<"result">>  => <<"ok">> }
           end,
-    json:encode(Msg).
+    json_encode(Msg).
+
+json_encode(Msg) ->
+    iolist_to_binary(json:encode(Msg)).
 
 error_code(mining_disabled  ) -> -32000;
 error_code(pool_exists      ) -> -32001;