diff --git a/lib/guardian/topic_guardian.rb b/lib/guardian/topic_guardian.rb
index 24b5eaa0de1..014e707afd5 100644
--- a/lib/guardian/topic_guardian.rb
+++ b/lib/guardian/topic_guardian.rb
@@ -84,6 +84,7 @@ module TopicGuardian
   end
 
   def can_convert_topic?(topic)
+    return false unless SiteSetting.enable_personal_messages?
     return false if topic.blank?
     return false if topic && topic.trashed?
     return false if Category.where("topic_id = ?", topic.id).exists?
diff --git a/spec/components/guardian_spec.rb b/spec/components/guardian_spec.rb
index 4603b006ef4..f96f4e001a0 100644
--- a/spec/components/guardian_spec.rb
+++ b/spec/components/guardian_spec.rb
@@ -1095,6 +1095,11 @@ describe Guardian do
     it 'returns true when an admin' do
       expect(Guardian.new(admin).can_convert_topic?(topic)).to be_truthy
     end
+
+    it 'returns false when personal messages are disabled' do
+      SiteSetting.enable_personal_messages = false
+      expect(Guardian.new(admin).can_convert_topic?(topic)).to be_falsey
+    end
   end
 
   describe 'can_edit?' do