diff --git a/Include/pyatomic.h b/Include/pyatomic.h
index b0028fd92fa..da45327b89c 100644
--- a/Include/pyatomic.h
+++ b/Include/pyatomic.h
@@ -64,7 +64,8 @@ _Py_ANNOTATE_MEMORY_ORDER(const volatile void *address, _Py_memory_order order)
     case _Py_memory_order_seq_cst:
         _Py_ANNOTATE_HAPPENS_BEFORE(address);
         break;
-    default:
+    case _Py_memory_order_relaxed:
+    case _Py_memory_order_acquire:
         break;
     }
     switch(order) {
@@ -73,7 +74,8 @@ _Py_ANNOTATE_MEMORY_ORDER(const volatile void *address, _Py_memory_order order)
     case _Py_memory_order_seq_cst:
         _Py_ANNOTATE_HAPPENS_AFTER(address);
         break;
-    default:
+    case _Py_memory_order_relaxed:
+    case _Py_memory_order_release:
         break;
     }
 }
diff --git a/Misc/ACKS b/Misc/ACKS
index 986debd4b65..acf214746ec 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -132,6 +132,7 @@ Titus Brown
 Oleg Broytmann
 Dave Brueck
 Francisco Martín Brugué
+Floris Bruynooghe
 Stan Bubrouski
 Erik de Bueger
 Jan-Hein Bührman
diff --git a/Misc/NEWS b/Misc/NEWS
index 183e4ed49a5..90c0f3b5567 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,10 @@ What's New in Python 3.3 Alpha 1?
 Core and Builtins
 -----------------
 
+- Issue #13338: Handle all enumerations in _Py_ANNOTATE_MEMORY_ORDER
+  to allow compiling extension modules with -Wswitch-enum on gcc.
+  Initial patch by Floris Bruynooghe.
+
 - Issue #10227: Add an allocation cache for a single slice object.  Patch by
   Stefan Behnel.