diff --git a/shakapacker.gemspec b/shakapacker.gemspec
index 1ad6961d0..68b83517e 100644
--- a/shakapacker.gemspec
+++ b/shakapacker.gemspec
@@ -29,7 +29,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "rubocop-performance"
 
   s.files = `git ls-files -z`.split("\x0").reject { |f|
-    f.match(%r{^(test|spec|features|tmp|node_modules|packages|coverage|Gemfile.lock|rakelib)/})
+    f.match(%r{^(test|spec|features|tmp|node_modules|packages|coverage|Gemfile.lock|rakelib)($|/)})
   } + Dir.glob("sig/**/*.rbs")
 
   s.test_files = `git ls-files -- test/*`.split("\n")