diff --git a/lib/stylesheet/manager.rb b/lib/stylesheet/manager.rb
index ea7de4dbe0f..2d5f3614d10 100644
--- a/lib/stylesheet/manager.rb
+++ b/lib/stylesheet/manager.rb
@@ -256,7 +256,18 @@ class Stylesheet::Manager
       raise "attempting to look up theme digest for invalid field"
     end
 
-    Digest::SHA1.hexdigest(scss.to_s + color_scheme_digest.to_s + settings_digest)
+    Digest::SHA1.hexdigest(scss.to_s + color_scheme_digest.to_s + settings_digest + plugins_digest)
+  end
+
+  # this protects us from situations where new versions of a plugin removed a file
+  # old instances may still be serving CSS and not aware of the change
+  # so we could end up poisoning the cache with a bad file that can not be removed
+  def plugins_digest
+    assets = []
+    assets += DiscoursePluginRegistry.stylesheets.to_a
+    assets += DiscoursePluginRegistry.mobile_stylesheets.to_a
+    assets += DiscoursePluginRegistry.desktop_stylesheets.to_a
+    Digest::SHA1.hexdigest(assets.sort.join)
   end
 
   def settings_digest
diff --git a/spec/components/stylesheet/manager_spec.rb b/spec/components/stylesheet/manager_spec.rb
index 07571887fa3..9e5b6ff3475 100644
--- a/spec/components/stylesheet/manager_spec.rb
+++ b/spec/components/stylesheet/manager_spec.rb
@@ -65,6 +65,30 @@ describe Stylesheet::Manager do
     expect(new_link).to include("/stylesheets/desktop_theme_#{theme.id}_")
   end
 
+  describe 'digest' do
+    after do
+      DiscoursePluginRegistry.stylesheets.delete "fake_file"
+    end
+
+    it 'can correctly account for plugins in digest' do
+
+      theme = Theme.create!(
+        name: 'parent',
+        user_id: -1
+      )
+
+      manager = Stylesheet::Manager.new(:desktop_theme, theme.key)
+      digest1 = manager.digest
+
+      DiscoursePluginRegistry.stylesheets.add "fake_file"
+
+      manager = Stylesheet::Manager.new(:desktop_theme, theme.key)
+      digest2 = manager.digest
+
+      expect(digest1).not_to eq(digest2)
+    end
+  end
+
   describe 'color_scheme_digest' do
     it "changes with category background image" do
       theme = Theme.new(