diff --git a/newrelic_rpm.gemspec b/newrelic_rpm.gemspec
index 75dbf75f1e..e5aa0280cc 100644
--- a/newrelic_rpm.gemspec
+++ b/newrelic_rpm.gemspec
@@ -39,7 +39,7 @@ Gem::Specification.new do |s|
     'homepage_uri' => 'https://newrelic.com/ruby'
   }
 
-  reject_list = File.read('./.build_ignore').split("\n")
+  reject_list = File.read(File.expand_path('../.build_ignore', __FILE__)).split("\n")
   file_list = `git ls-files -z`.split("\x0").reject { |f| reject_list.any? { |rf| f.start_with?(rf) } }
   # test/agent_helper.rb is a requirement for the NewRelic::Agent.require_test_helper public API
   test_helper_path = 'test/agent_helper.rb'
diff --git a/test/new_relic/gemspec_files_test.rb b/test/new_relic/gemspec_files_test.rb
index 867b54d812..2cb6be605d 100644
--- a/test/new_relic/gemspec_files_test.rb
+++ b/test/new_relic/gemspec_files_test.rb
@@ -7,14 +7,16 @@
 class GemspecFilesTest < Minitest::Test
   def test_the_test_agent_helper_is_shipped_in_the_gem_files
     skip if defined?(Rails::VERSION)
-
-    agent_helper_file = 'test/agent_helper.rb'
+    skip 'Gemspec test requires a newer version of Rubygems' unless Gem.respond_to?(:open_file)
 
     gem_spec_file_path = File.expand_path('../../../newrelic_rpm.gemspec', __FILE__)
 
-    gem_spec = Gem::Specification.load(gem_spec_file_path)
+    Dir.chdir(File.dirname(gem_spec_file_path)) do
+      gem_spec = eval(Gem.open_file(gem_spec_file_path, 'r:UTF-8:-', &:read))
 
-    assert_equal('newrelic_rpm', gem_spec.name)
-    assert_includes(gem_spec.files, agent_helper_file)
+      assert gem_spec, "Failed to parse '#{gem_spec_file_path}'"
+      assert_equal('newrelic_rpm', gem_spec.name)
+      assert_includes(gem_spec.files, 'test/agent_helper.rb')
+    end
   end
 end