diff --git a/qa/rpc-tests/test_framework/authproxy.py b/qa/rpc-tests/test_framework/authproxy.py
index 1eb277259..e5f7ab365 100644
--- a/qa/rpc-tests/test_framework/authproxy.py
+++ b/qa/rpc-tests/test_framework/authproxy.py
@@ -154,6 +154,11 @@ class AuthServiceProxy(object):
             raise JSONRPCException({
                 'code': -342, 'message': 'missing HTTP response from server'})
 
+        content_type = http_response.getheader('Content-Type')
+        if content_type != 'application/json':
+            raise JSONRPCException({
+                'code': -342, 'message': 'non-JSON HTTP response with \'%i %s\' from server' % (http_response.status, http_response.reason)})
+
         responsedata = http_response.read().decode('utf8')
         response = json.loads(responsedata, parse_float=decimal.Decimal)
         if "error" in response and response["error"] is None: