diff --git a/boards/models/post/__init__.py b/boards/models/post/__init__.py
--- a/boards/models/post/__init__.py
+++ b/boards/models/post/__init__.py
@@ -314,6 +314,11 @@ class Post(models.Model, Viewable):
             if image_refs_count == 1:
                 image.delete()
 
+        for attachment in self.attachments.all():
+            attachment_refs_count = Post.objects.filter(attachments__in=[attachment]).count()
+            if attachment_refs_count == 1:
+                attachment.delete()
+
         thread = self.get_thread()
         thread.last_edit_time = timezone.now()
         thread.save()