diff --git a/src/couch_replicator_api_wrap.erl b/src/couch_replicator_api_wrap.erl
index ae4f16e..22a3b78 100644
--- a/src/couch_replicator_api_wrap.erl
+++ b/src/couch_replicator_api_wrap.erl
@@ -154,7 +154,7 @@
         end
     end);
 get_pending_count(#httpdb{} = Db, Seq) ->
-    Options = [{path, "_changes"}, {qs, [{"since", Seq}, {"limit", "0"}]}],
+    Options = [{path, "_changes"}, {qs, [{"since", ?JSON_ENCODE(Seq)}, {"limit", "0"}]}],
     send_req(Db, Options, fun(200, _, {Props}) ->
         {ok, couch_util:get_value(<<"pending">>, Props, null)}
     end);