diff --git a/docs/source/explanations/specialized-formats.md b/docs/source/explanations/specialized-formats.md
index 3ffcd6dda..7bf494e47 100644
--- a/docs/source/explanations/specialized-formats.md
+++ b/docs/source/explanations/specialized-formats.md
@@ -88,7 +88,8 @@ trees:
     tree: tiled.catalog:from_uri
     args:
       uri: ./catalog.db
-        - readable_storage: ./data/
+        readable_storage:
+          - ./data/
       adapters_by_mimetype:
         application/x-xdi: tiled.examples.xdi:read_xdi
 ```