diff --git a/app/models/post.rb b/app/models/post.rb
index 30ebaf01630..e1a3a1f391e 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -650,6 +650,10 @@ class Post < ActiveRecord::Base
       baked_version: BAKED_VERSION
     )
 
+    if is_first_post?
+      topic.update_excerpt(excerpt_for_topic)
+    end
+
     if invalidate_broken_images
       custom_fields.delete(BROKEN_IMAGES)
       save_custom_fields
diff --git a/app/models/topic.rb b/app/models/topic.rb
index f02b4fc030f..38affdb327b 100644
--- a/app/models/topic.rb
+++ b/app/models/topic.rb
@@ -1476,6 +1476,13 @@ class Topic < ActiveRecord::Base
     private_topic
   end
 
+  def update_excerpt(excerpt)
+    update_column(:excerpt, excerpt)
+    if archetype == "banner"
+      ApplicationController.banner_json_cache.clear
+    end
+  end
+
   def pm_with_non_human_user?
     sql = <<~SQL
     SELECT 1 FROM topics
diff --git a/lib/post_revisor.rb b/lib/post_revisor.rb
index 3c9ec277cdb..d610fccf375 100644
--- a/lib/post_revisor.rb
+++ b/lib/post_revisor.rb
@@ -567,11 +567,7 @@ class PostRevisor
   end
 
   def update_topic_excerpt
-    excerpt = @post.excerpt_for_topic
-    @topic.update_column(:excerpt, excerpt)
-    if @topic.archetype == "banner"
-      ApplicationController.banner_json_cache.clear
-    end
+    @topic.update_excerpt(@post.excerpt_for_topic)
   end
 
   def update_category_description
diff --git a/spec/models/post_spec.rb b/spec/models/post_spec.rb
index d0e2aba6319..5bc5206bced 100644
--- a/spec/models/post_spec.rb
+++ b/spec/models/post_spec.rb
@@ -1195,6 +1195,25 @@ describe Post do
       expect(post.cooked).to eq(first_cooked)
       expect(result).to eq(true)
     end
+
+    it "updates the topic excerpt at the same time if it is the OP" do
+      post = create_post
+      post.topic.update(excerpt: "test")
+      DB.exec("UPDATE posts SET cooked = 'frogs' WHERE id = ?", [ post.id ])
+      post.reload
+      result = post.rebake!
+      post.topic.reload
+      expect(post.topic.excerpt).not_to eq("test")
+    end
+
+    it "does not update the topic excerpt if the post is not the OP" do
+      post = create_post
+      post2 = create_post
+      post.topic.update(excerpt: "test")
+      result = post2.rebake!
+      post.topic.reload
+      expect(post.topic.excerpt).to eq("test")
+    end
   end
 
   describe "#set_owner" do