diff --git a/50_bubble.py b/50_bubble.py
index 2c4a41b..546ad6c 100644
--- a/50_bubble.py
+++ b/50_bubble.py
@@ -18,7 +18,7 @@ from utils import *
 from worker import *
 
 
-__version__ = '8.3'
+__version__ = '8.4'
 
 
 class Bubble:
diff --git a/composer.py b/composer.py
index 72e2708..da53fa0 100644
--- a/composer.py
+++ b/composer.py
@@ -343,7 +343,10 @@ def make_composer_page(session):
             return 50, "Cannot move to an issue tracker subspace"
         if dst_sub.owner and dst_sub.owner != post.user:
             return 50, "Cannot move to another user's subspace"
+
+        oldsub_id = post.subspace
         db.update_post(post, subspace_id=dst_sub.id)
+        db.move_comments(post, oldsub_id, dst_sub.id)
 
         # Notify as if the post was new.
         db.notify_followed_about_post(post)
diff --git a/model.py b/model.py
index b904e71..2268de5 100644
--- a/model.py
+++ b/model.py
@@ -2297,6 +2297,12 @@ class Database:
                 self.update_post_summary(post)
             self.unpublish_if_empty(post)
 
+    def move_comments(self, post: Post, oldsub_id, newsub_id):
+        cur = self.conn.cursor()
+        cur.execute("UPDATE posts SET subspace=? WHERE subspace=? AND parent=?",
+                    (newsub_id, oldsub_id, post.id))
+        self.commit()
+
     def notify_mentioned(self, post, content, old_content=None):
         names = parse_at_names(content)
         post_user = self.get_user(id=post.user)