diff --git a/src/ablog/post.py b/src/ablog/post.py
index a010a2aa..1b3c6aa6 100644
--- a/src/ablog/post.py
+++ b/src/ablog/post.py
@@ -38,7 +38,7 @@
 
 
 def _split(a):
-    return {s.strip() for s in (a or "").split(",")}
+    return [s.strip() for s in (a or "").split(",")]
 
 
 class PostNode(nodes.Element):