diff --git a/Include/pyatomic.h b/Include/pyatomic.h
index b0028fd..da45327 100644
--- a/Include/pyatomic.h
+++ b/Include/pyatomic.h
@@ -64,7 +64,8 @@
     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 @@
     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 a82e0c9..c66edb7 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -124,6 +124,7 @@
 Oleg Broytmann
 Dave Brueck
 Francisco Martín Brugué
+Floris Bruynooghe
 Stan Bubrouski
 Erik de Bueger
 Dick Bulterman
diff --git a/Misc/NEWS b/Misc/NEWS
index 513984d..c3765dd 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,10 @@
 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 #13333: The UTF-7 decoder now accepts lone surrogates (the encoder
   already accepts them).