diff --git a/test/mcp/client/stdio_test.rb b/test/mcp/client/stdio_test.rb
index 6b1b92fb..ce01fb91 100644
--- a/test/mcp/client/stdio_test.rb
+++ b/test/mcp/client/stdio_test.rb
@@ -73,6 +73,7 @@ def test_send_request_starts_process_and_returns_response
         stdin_write.close
         stdout_read.close
         stdout_write.close
+        stderr_read.close
       end
 
       def test_send_request_initializes_session_on_first_call