diff --git a/test/-ext-/gvl/test_last_thread.rb b/test/-ext-/gvl/test_last_thread.rb
index df25165b4b..cf5f28f4b6 100644
--- a/test/-ext-/gvl/test_last_thread.rb
+++ b/test/-ext-/gvl/test_last_thread.rb
@@ -15,7 +15,7 @@ class TestLastThread < Test::Unit::TestCase
       t1 = Time.now
       t = t1 - t0
 
-      assert_operator(t, :>=, 1)
+      assert_in_delta(1.0, t, 0.16)
     end;
   end
 end