diff --git a/test/-ext-/debug/test_profile_frames.rb b/test/-ext-/debug/test_profile_frames.rb
index e66413c228..b44b14d851 100644
--- a/test/-ext-/debug/test_profile_frames.rb
+++ b/test/-ext-/debug/test_profile_frames.rb
@@ -182,7 +182,9 @@ class TestProfileFrames < Test::Unit::TestCase
       assert_equal(full_labels[i], frame)
     end
 
+  ensure
     th.kill
+    th.join
   end