diff --git a/test/ruby/test_thread.rb b/test/ruby/test_thread.rb
index 3695f6e..5912929 100644
--- a/test/ruby/test_thread.rb
+++ b/test/ruby/test_thread.rb
@@ -557,7 +557,9 @@ def test_thread_local_fetch
     assert_equal(3, t.fetch("qux") {x = 3})
     assert_equal(3, x)
 
-    assert_raise(KeyError) {t.fetch(:qux)}
+    e = assert_raise(KeyError) {t.fetch(:qux)}
+    assert_equal(:qux, e.key)
+    assert_equal(t, e.receiver)
   ensure
     t.kill if t
   end
diff --git a/thread.c b/thread.c
index 2460d7e..7df1a66 100644
--- a/thread.c
+++ b/thread.c
@@ -3168,7 +3168,7 @@ rb_thread_fetch(int argc, VALUE *argv, VALUE self)
 	return rb_yield(key);
     }
     else if (argc == 1) {
-	rb_raise(rb_eKeyError, "key not found: %"PRIsVALUE, key);
+	rb_key_err_raise(rb_sprintf("key not found: \"%"PRIsVALUE"\"", key), self, key);
     }
     else {
 	return argv[1];