diff --git a/synapse/appservice/api.py b/synapse/appservice/api.py
index 6192813c03..c2179f8d55 100644
--- a/synapse/appservice/api.py
+++ b/synapse/appservice/api.py
@@ -80,11 +80,11 @@ class ApplicationServiceApi(SimpleHttpClient):
         response = None
         try:
             response = yield self.put_json(
-                uri,
-                {
+                uri=uri,
+                json_body={
                     "events": events
                 },
-                {
+                args={
                     "access_token": service.hs_token
                 })
             if response:  # just an empty json object
diff --git a/synapse/http/client.py b/synapse/http/client.py
index 575510637e..7b23116556 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -95,7 +95,8 @@ class SimpleHttpClient(object):
             Deferred: Succeeds when we get *any* 2xx HTTP response, with the
             HTTP body as JSON.
         Raises:
-            On a non-2xx HTTP response.
+            On a non-2xx HTTP response. The response body will be used as the
+            error message.
         """
         if len(args):
             query_bytes = urllib.urlencode(args, True)