diff --git a/demo/clean.sh b/demo/clean.sh
index c5dabd4767..418ca9457e 100755
--- a/demo/clean.sh
+++ b/demo/clean.sh
@@ -11,7 +11,9 @@ if [ -f $PID_FILE ]; then
     exit 1
 fi
 
-find "$DIR" -name "*.log" -delete
-find "$DIR" -name "*.db" -delete
+for port in 8080 8081 8082; do
+    rm -rf $DIR/$port
+    rm -rf $DIR/media_store.$port
+done
 
 rm -rf $DIR/etc
diff --git a/demo/start.sh b/demo/start.sh
index b9cc14b9d2..b5dea5e176 100755
--- a/demo/start.sh
+++ b/demo/start.sh
@@ -8,14 +8,6 @@ cd "$DIR/.."
 
 mkdir -p demo/etc
 
-# Check the --no-rate-limit param
-PARAMS=""
-if [ $# -eq 1 ]; then
-    if [ $1 = "--no-rate-limit" ]; then
-	    PARAMS="--rc-messages-per-second 1000 --rc-message-burst-count 1000"
-    fi
-fi
-
 export PYTHONPATH=$(readlink -f $(pwd))
 
 
@@ -35,6 +27,15 @@ for port in 8080 8081 8082; do
         -H "localhost:$https_port" \
         --config-path "$DIR/etc/$port.config" \
 
+    # Check script parameters
+    if [ $# -eq 1 ]; then
+        if [ $1 = "--no-rate-limit" ]; then
+            # Set high limits in config file to disable rate limiting
+            perl -p -i -e 's/rc_messages_per_second.*/rc_messages_per_second: 1000/g' $DIR/etc/$port.config
+            perl -p -i -e 's/rc_message_burst_count.*/rc_message_burst_count: 1000/g' $DIR/etc/$port.config
+        fi
+    fi
+
     python -m synapse.app.homeserver \
         --config-path "$DIR/etc/$port.config" \
         -D \
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index c99fda849e..408c3b5e65 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -90,7 +90,9 @@ class Cache(object):
     def invalidate(self, key):
         self.check_thread()
         if not isinstance(key, tuple):
-            raise ValueError("keyargs must be a tuple.")
+            raise TypeError(
+                "The cache key must be a tuple not %r" % (type(key),)
+            )
 
         # Increment the sequence number so that any SELECT statements that
         # raced with the INSERT don't update the cache (SYN-369)
diff --git a/tests/test_distributor.py b/tests/test_distributor.py
index 6a0095d850..8ed48cfb70 100644
--- a/tests/test_distributor.py
+++ b/tests/test_distributor.py
@@ -73,8 +73,8 @@ class DistributorTestCase(unittest.TestCase):
             yield d
             self.assertTrue(d.called)
 
-            observers[0].assert_called_once("Go")
-            observers[1].assert_called_once("Go")
+            observers[0].assert_called_once_with("Go")
+            observers[1].assert_called_once_with("Go")
 
             self.assertEquals(mock_logger.warning.call_count, 1)
             self.assertIsInstance(mock_logger.warning.call_args[0][0],