diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index 8559d06b7f7b479daa10e59add045a97beeed2ed..056d446e42f26b858244f7a1f1f9ca13098ad0a3 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -169,8 +169,9 @@ class MatrixFederationHttpClient(object):
         else:
             # :'(
             # Update transactions table?
+            body = yield readBody(response)
             raise HttpResponseException(
-                response.code, response.phrase, response
+                response.code, response.phrase, body
             )
 
         defer.returnValue(response)