diff --git a/apps/iot/src/iot_host.erl b/apps/iot/src/iot_host.erl
index 1a44851..bf15cc3 100644
--- a/apps/iot/src/iot_host.erl
+++ b/apps/iot/src/iot_host.erl
@@ -382,7 +382,7 @@ code_change(_OldVsn, StateName, State = #state{}, _Extra) ->
 %%%===================================================================
 
 convert_fields(#{<<"key">> := Key, <<"value">> := Value, <<"unit">> := Unit}) ->
-    #{Key => jiffy:encode(#{<<"value">> => Value, <<"unit">> := Unit}, [force_utf8])};
+    #{Key => jiffy:encode(#{<<"value">> => Value, <<"unit">> => Unit}, [force_utf8])};
 convert_fields(#{<<"key">> := Key, <<"value">> := Value}) ->
     #{Key => Value}.