diff --git a/django/applications/catmaid/control/node.py b/django/applications/catmaid/control/node.py
index 3820d543d9..5b0e771a76 100644
--- a/django/applications/catmaid/control/node.py
+++ b/django/applications/catmaid/control/node.py
@@ -214,7 +214,7 @@ def get_tuples(self, params, project_id, explicit_treenode_ids,
                 if tuples[0] != b'\x95':
                     raise ValueError("Unexpected cached Msgpack tuple format")
 
-                extra_msgpack = msgpack.packb(extra_tuples)
+                extra_msgpack = msgpack.packb([extra_tuples])
 
                 # Extend the five-element list with extra tuples by making it a
                 # six element list and just appending the extra list