diff --git a/app/models/topic.rb b/app/models/topic.rb
index b99b9c7015c..208b639d505 100644
--- a/app/models/topic.rb
+++ b/app/models/topic.rb
@@ -74,6 +74,7 @@ class Topic < ActiveRecord::Base
                     presence: true,
                     topic_title_length: true,
                     censored_words: true,
+                    watched_words: true,
                     quality_title: { unless: :private_message? },
                     max_emojis: true,
                     unique_among: { unless: Proc.new { |t| (SiteSetting.allow_duplicate_topic_titles? || t.private_message?) },
diff --git a/lib/validators/post_validator.rb b/lib/validators/post_validator.rb
index 09c564b3b19..dc391b63bf5 100644
--- a/lib/validators/post_validator.rb
+++ b/lib/validators/post_validator.rb
@@ -36,7 +36,7 @@ class Validators::PostValidator < ActiveModel::Validator
     return if options[:skip_post_body] || post.topic&.pm_with_non_human_user?
     stripped_length(post)
     raw_quality(post)
-    watched_words(post)
+    WatchedWordsValidator.new(attributes: [:raw]).validate(post) if !post.acting_user&.staged
   end
 
   def stripped_length(post)
@@ -59,19 +59,6 @@ class Validators::PostValidator < ActiveModel::Validator
     post.errors.add(:raw, I18n.t(:is_invalid)) unless sentinel.valid?
   end
 
-  def watched_words(post)
-    if !post.acting_user&.staged && matches = WordWatcher.new(post.raw).should_block?.presence
-      if matches.size == 1
-        key = 'contains_blocked_word'
-        translation_args = { word: matches[0] }
-      else
-        key = 'contains_blocked_words'
-        translation_args = { words: matches.join(', ') }
-      end
-      post.errors.add(:base, I18n.t(key, translation_args))
-    end
-  end
-
   # Ensure maximum amount of mentions in a post
   def max_mention_validator(post)
     return if post.acting_user.try(:staff?)
diff --git a/lib/validators/watched_words_validator.rb b/lib/validators/watched_words_validator.rb
new file mode 100644
index 00000000000..cfa7e5a6b66
--- /dev/null
+++ b/lib/validators/watched_words_validator.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class WatchedWordsValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    if matches = WordWatcher.new(value).should_block?.presence
+      if matches.size == 1
+        key = 'contains_blocked_word'
+        translation_args = { word: matches[0] }
+      else
+        key = 'contains_blocked_words'
+        translation_args = { words: matches.join(', ') }
+      end
+      record.errors.add(:base, I18n.t(key, translation_args))
+    end
+  end
+end
diff --git a/spec/models/topic_spec.rb b/spec/models/topic_spec.rb
index e9da4a7c639..0c3f6383531 100644
--- a/spec/models/topic_spec.rb
+++ b/spec/models/topic_spec.rb
@@ -86,6 +86,22 @@ describe Topic do
           end
         end
       end
+
+      describe 'blocked words' do
+        describe 'when title contains watched words' do
+          it 'should not be valid' do
+            Fabricate(:watched_word, word: 'pineapple', action: WatchedWord.actions[:block])
+
+            topic.title = 'pen PinEapple apple pen is a complete sentence'
+
+            expect(topic).to_not be_valid
+
+            expect(topic.errors.full_messages.first).to include(I18n.t(
+              'contains_blocked_word', word: 'PinEapple'
+            ))
+          end
+        end
+      end
     end
   end