diff --git a/src/bson_binary.erl b/src/bson_binary.erl
index 49e3719..6ef9b86 100644
--- a/src/bson_binary.erl
+++ b/src/bson_binary.erl
@@ -52,7 +52,7 @@ get_fields(<<>>, Acc) when is_map(Acc) -> Acc;
 get_fields(<<>>, Acc) -> lists:reverse(Acc);
 get_fields(Bin, Acc) when is_map(Acc) ->
   {Name, Value, Bin1} = get_field(Bin, map),
-  get_fields(Bin1, Acc#{Name => Value});
+  get_fields(Bin1, maps:put(Name,Value,Acc));
 get_fields(Bin, Acc) ->
   {Name, Value, Bin1} = get_field(Bin, normal),
   get_fields(Bin1, [Value, Name | Acc]).
@@ -225,4 +225,4 @@ put_oid(<<Oid:12/binary>>) -> Oid.
 
 %% @private
 -spec get_oid(binary()) -> {<<_:96>>, binary()}.
-get_oid(<<Oid:12/binary, Bin/binary>>) -> {Oid, Bin}.
\ No newline at end of file
+get_oid(<<Oid:12/binary, Bin/binary>>) -> {Oid, Bin}.