diff --git a/test/rake/test_rake_functional.rb b/test/rake/test_rake_functional.rb
index f2ce2f7..c5d832f 100644
--- a/test/rake/test_rake_functional.rb
+++ b/test/rake/test_rake_functional.rb
@@ -414,7 +414,7 @@ class TestRakeFunctional < Rake::TestCase
   end
 
   def can_detect_signals?
-    system "ruby -e 'Process.kill \"TERM\", $$'"
+    system RUBY, '-e', 'Process.kill "TERM", $$'
     status = $?
     if @verbose
       puts "    SIG status = #{$?.inspect}"