diff --git a/Library/Homebrew/test/cmd/install_spec.rb b/Library/Homebrew/test/cmd/install_spec.rb
index e9b9949af0..2a13c187bd 100644
--- a/Library/Homebrew/test/cmd/install_spec.rb
+++ b/Library/Homebrew/test/cmd/install_spec.rb
@@ -84,7 +84,7 @@ describe "brew install" do
     expect(HOMEBREW_CELLAR/"testball1/0.1/bin/test.dSYM").to be_a_directory if OS.mac?
     if OS.linux?
       expect { system_command("objdump", "-h", "${HOMEBREW_CELLAR}/testball1/0.1/bin/test") }
-        .to output(%r{\.debug}).to_stdout
+        .to output(/\.debug/).to_stdout
     end
     expect(HOMEBREW_CACHE/"Sources/testball1").to be_a_directory
   end