diff --git a/lib/webpacker/sri_helper_extensions.rb b/lib/webpacker/sri_helper_extensions.rb
index 74b7bdfc..d72dee7b 100644
--- a/lib/webpacker/sri_helper_extensions.rb
+++ b/lib/webpacker/sri_helper_extensions.rb
@@ -24,4 +24,6 @@ module Webpacker::SriHelperExtensions
   end
 end
 
-Sprockets::Rails::Helper.prepend(Webpacker::SriHelperExtensions)
+if Sprockets::Rails::Helper.ancestors.map(&:name).exclude?(Webpacker::SriHelperExtensions.name)
+  Sprockets::Rails::Helper.prepend(Webpacker::SriHelperExtensions)
+end
diff --git a/lib/webpacker/sri_manifest_extensions.rb b/lib/webpacker/sri_manifest_extensions.rb
index 143bf7a5..a4199a09 100644
--- a/lib/webpacker/sri_manifest_extensions.rb
+++ b/lib/webpacker/sri_manifest_extensions.rb
@@ -26,4 +26,6 @@ module Webpacker::SriManifestExtensions
   end
 end
 
-Webpacker::Manifest.prepend(Webpacker::SriManifestExtensions)
+if Webpacker::Manifest.ancestors.map(&:name).exclude?(Webpacker::SriManifestExtensions.name)
+  Webpacker::Manifest.prepend(Webpacker::SriManifestExtensions)
+end