diff --git a/test/test_thread_pool.rb b/test/test_thread_pool.rb
index 18901d6a..db399d2b 100644
--- a/test/test_thread_pool.rb
+++ b/test/test_thread_pool.rb
@@ -78,7 +78,10 @@ class TestThreadPool < Minitest::Test
     end
 
     pool.trim
-    pool.instance_variable_get(:@workers).first.join
+    
+    # wait/join required here for MRI, JRuby slow enough to error here
+    worker = pool.instance_variable_get(:@workers).first
+    worker.join if worker
 
     assert_equal 0, pool.spawned
   end