diff --git a/synapse/rest/directory.py b/synapse/rest/directory.py
index 5aaac05e2863bfb5b4283a8708a7e453a75d1b73..35300c6a6fc257b7e5e88f44aec5a6fe2c40d948 100644
--- a/synapse/rest/directory.py
+++ b/synapse/rest/directory.py
@@ -36,7 +36,9 @@ class ClientDirectoryServer(RestServlet):
 
     @defer.inlineCallbacks
     def on_GET(self, request, room_alias):
-        room_alias = self.hs.parse_roomalias(urllib.unquote(room_alias))
+        room_alias = self.hs.parse_roomalias(
+            urllib.unquote(room_alias).decode("utf-8")
+        )
 
         dir_handler = self.handlers.directory_handler
         res = yield dir_handler.get_association(room_alias)
@@ -54,7 +56,9 @@ class ClientDirectoryServer(RestServlet):
 
         logger.debug("Got content: %s", content)
 
-        room_alias = self.hs.parse_roomalias(urllib.unquote(room_alias))
+        room_alias = self.hs.parse_roomalias(
+            urllib.unquote(room_alias).decode("utf-8")
+        )
 
         logger.debug("Got room name: %s", room_alias.to_string())
 
@@ -93,7 +97,9 @@ class ClientDirectoryServer(RestServlet):
 
         dir_handler = self.handlers.directory_handler
 
-        room_alias = self.hs.parse_roomalias(urllib.unquote(room_alias))
+        room_alias = self.hs.parse_roomalias(
+            urllib.unquote(room_alias).decode("utf-8")
+        )
 
         yield dir_handler.delete_association(
             user.to_string(), room_alias