diff --git a/test/run_test.py b/test/run_test.py
index 5aec0357445..4f90b6ded11 100755
--- a/test/run_test.py
+++ b/test/run_test.py
@@ -1321,6 +1321,7 @@ def must_serial(file: Union[str, ShardedTest]) -> bool:
         or file in CI_SERIAL_LIST
         or file in JIT_EXECUTOR_TESTS
         or file in ONNX_SERIAL_LIST
+        or NUM_PROCS == 1
     )