diff --git a/synapse/handlers/appservice.py b/synapse/handlers/appservice.py
index e68628bdfd..a0375f7e3b 100644
--- a/synapse/handlers/appservice.py
+++ b/synapse/handlers/appservice.py
@@ -176,13 +176,16 @@ class ApplicationServicesHandler(object):
         defer.returnValue(ret)
 
     @defer.inlineCallbacks
-    def get_3pe_protocols(self):
+    def get_3pe_protocols(self, only_protocol=None):
         services = yield self.store.get_app_services()
         protocols = {}
 
         # Collect up all the individual protocol responses out of the ASes
         for s in services:
             for p in s.protocols:
+                if only_protocol is not None and p != only_protocol:
+                    continue
+
                 info = yield self.appservice_api.get_3pe_protocol(s, p)
 
                 # Ignore any result that doesn't contain an "instances" list
diff --git a/synapse/rest/client/v2_alpha/thirdparty.py b/synapse/rest/client/v2_alpha/thirdparty.py
index 48d8543e76..6bf9eb10ae 100644
--- a/synapse/rest/client/v2_alpha/thirdparty.py
+++ b/synapse/rest/client/v2_alpha/thirdparty.py
@@ -55,7 +55,9 @@ class ThirdPartyProtocolServlet(RestServlet):
     def on_GET(self, request, protocol):
         yield self.auth.get_user_by_req(request)
 
-        protocols = yield self.appservice_handler.get_3pe_protocols()
+        protocols = yield self.appservice_handler.get_3pe_protocols(
+            only_protocol=protocol,
+        )
         if protocol in protocols:
             defer.returnValue((200, protocols[protocol]))
         else: