diff --git a/files/routes/posts.py b/files/routes/posts.py
index 9e786c6046..1776a8622a 100644
--- a/files/routes/posts.py
+++ b/files/routes/posts.py
@@ -806,7 +806,8 @@ def submit_post(v, sub=None):
 	if not sub: sub = request.values.get("sub")
 
 	if sub:
-		g.db.query(Sub.name).filter_by(name=sub.strip().lower()).one_or_none()
+		sub = g.db.query(Sub.name).filter_by(name=sub.strip().lower()).one_or_none()
+		if not sub: abort(404)
 		sub = sub[0]
 	else: sub = None