diff --git a/pep-0556.rst b/pep-0556.rst
index 23f04aff1..d3037b418 100644
--- a/pep-0556.rst
+++ b/pep-0556.rst
@@ -92,7 +92,7 @@ when called, and only return when the GC run is finished.
 
 
 New public APIs
-===============
+---------------
 
 Two new Python APIs are added to the ``gc`` module:
 
@@ -106,7 +106,7 @@ It is allowed to switch back and forth between modes of operation.
 
 
 Intended use
-============
+------------
 
 Given the per-process nature of the switch and its repercussions on
 semantics of all finalization callbacks, it is recommended that it is
@@ -118,7 +118,7 @@ doing so.
 
 
 Non-goals
-=========
+---------
 
 This PEP does not address reentrancy issues with other kinds of
 asynchronous code execution (for example signal handlers registered
@@ -186,7 +186,7 @@ object when called inside a finalization callback in the GC thread.
 
 
 Pseudo-code
-===========
+-----------
 
 Here is a proposed pseudo-code for the main primitives, public and internal,
 required for implementing this PEP.  All of them will be implemented in C