diff --git a/synapse/http/client.py b/synapse/http/client.py
index dea61ba1e0..e2fdded673 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -361,7 +361,7 @@ class IdentityServerHttpClient(BaseHttpClient):
         defer.returnValue(json.loads(body))
 
 
-class CaptchaServerHttpClient(MatrixHttpClient):
+class CaptchaServerHttpClient(BaseHttpClient):
     """Separate HTTP client for talking to google's captcha servers"""
 
     def _getEndpoint(self, reactor, destination):