diff --git a/app/models/person.rb b/app/models/person.rb
index 5042a45e50b..7bc32c51419 100644
--- a/app/models/person.rb
+++ b/app/models/person.rb
@@ -154,7 +154,9 @@ def downcase_diaspora_handle
   # @param [Post] the post for which we query mentionable in comments people
   # @return [Person::ActiveRecord_Relation]
   scope :allowed_to_be_mentioned_in_a_comment_to, ->(post) {
-    allowed = if post.public?
+    allowed = if post.nil?
+                none
+              elsif post.public?
                 all
               else
                 left_join_visible_post_interactions_on_authorship(post.id)
diff --git a/spec/models/notifications/mentioned_spec.rb b/spec/models/notifications/mentioned_spec.rb
index b1567f80dfc..90569b5459b 100644
--- a/spec/models/notifications/mentioned_spec.rb
+++ b/spec/models/notifications/mentioned_spec.rb
@@ -63,5 +63,16 @@ def self.filter_mentions(mentions, *)
       expect(TestNotification).not_to receive(:create_notification)
       TestNotification.notify(status_message, nil)
     end
+
+    it "doesn't create a notification for a mention in a comment of an already deleted post" do
+      post = FactoryGirl.create(:status_message, public: true)
+      comment = FactoryGirl.create(:comment, commentable: post, text: text_mentioning(alice))
+      post.delete
+      comment.reload
+
+      expect {
+        Notifications::MentionedInComment.notify(comment, [alice])
+      }.to_not change(Notification, :count)
+    end
   end
 end