diff --git a/lib/jasmine/headless/railtie.rb b/lib/jasmine/headless/railtie.rb
index ee857a6..8c3908f 100644
--- a/lib/jasmine/headless/railtie.rb
+++ b/lib/jasmine/headless/railtie.rb
@@ -31,7 +31,7 @@ module Jasmine
         if Rails.version >= "3.1.0"
           desc 'Force generate static assets without an MD5 hash, all assets end with -test.<ext>'
           task 'assets:precompile:for_testing' => :environment do
-            Rails.application.assets.instance_variable_set(:@digest_class, Digest::JasmineTest)
+            Rails.application.assets.digest_class = Digest::JasmineTest
 
             Rake::Task['assets:precompile'].invoke
           end