diff --git a/Modules/_posixsubprocess.c b/Modules/_posixsubprocess.c
index 44e1613..c93f537 100644
--- a/Modules/_posixsubprocess.c
+++ b/Modules/_posixsubprocess.c
@@ -577,6 +577,8 @@
         /* Equivalent to:  */
         /*  tuple(PyUnicode_FSConverter(arg) for arg in process_args)  */
         fast_args = PySequence_Fast(process_args, "argv must be a tuple");
+        if (fast_args == NULL)
+            goto cleanup;
         num_args = PySequence_Fast_GET_SIZE(fast_args);
         converted_args = PyTuple_New(num_args);
         if (converted_args == NULL)