fix "Title underline too short" sphinx warning
diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst
index cc8085f..97c0e03 100644
--- a/Doc/library/subprocess.rst
+++ b/Doc/library/subprocess.rst
@@ -240,7 +240,7 @@
 
 
 Popen Constructor
-^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^
 
 The underlying process creation and management in this module is handled by
 the :class:`Popen` class. It offers a lot of flexibility so that developers