diff --git a/app/models/category.rb b/app/models/category.rb
index adafc49a0f2..0efbb5f3ed8 100644
--- a/app/models/category.rb
+++ b/app/models/category.rb
@@ -70,6 +70,7 @@ class Category < ActiveRecord::Base
 
   after_create :create_category_definition
   after_destroy :trash_category_definition
+  after_destroy :clear_related_site_settings
 
   before_save :apply_permissions
   before_save :downcase_email
@@ -312,6 +313,12 @@ class Category < ActiveRecord::Base
     self.topic&.trash!
   end
 
+  def clear_related_site_settings
+    if self.id == SiteSetting.general_category_id
+      SiteSetting.general_category_id = -1
+    end
+  end
+
   def topic_url
     if has_attribute?("topic_slug")
       Topic.relative_url(topic_id, read_attribute(:topic_slug))
diff --git a/spec/models/category_spec.rb b/spec/models/category_spec.rb
index 942b38180cd..da0cf3bb4a4 100644
--- a/spec/models/category_spec.rb
+++ b/spec/models/category_spec.rb
@@ -1286,4 +1286,16 @@ RSpec.describe Category do
       end
     end
   end
+
+  describe '#deleting the general category' do
+    fab!(:category) { Fabricate(:category) }
+
+    it 'should empty out the general_category_id site_setting' do
+      SiteSetting.general_category_id = category.id
+      category.destroy
+
+      expect(SiteSetting.general_category_id).to_not eq(category.id)
+      expect(SiteSetting.general_category_id).to be < 1
+    end
+  end
 end