diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst
index 9f4b904..b557bcd 100644
--- a/Doc/library/subprocess.rst
+++ b/Doc/library/subprocess.rst
@@ -376,6 +376,9 @@
 
    The process ID of the child process.
 
+   Note that if you set the *shell* argument to ``True``, this is the process ID
+   of the spawned shell.
+
 
 .. attribute:: Popen.returncode