diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index 53064562e1b..941da0b56d4 100644
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -2181,7 +2181,12 @@ static void CData_MallocBuffer(CDataObject *obj, StgDictObject *dict)
 	if ((size_t)dict->size <= sizeof(obj->b_value)) {
 		/* No need to call malloc, can use the default buffer */
 		obj->b_ptr = (char *)&obj->b_value;
-		/* XXX(nnorwitz): shouldn't b_needsfree be 0? */
+		/* The b_needsfree flag does not mean that we actually did
+		   call PyMem_Malloc to allocate the memory block; instead it
+		   means we are the *owner* of the memory and are responsible
+		   for freeing resources associated with the memory.  This is
+		   also the reason that b_needsfree is exposed to Python.
+		 */
 		obj->b_needsfree = 1;
 	} else {
 		/* In python 2.4, and ctypes 0.9.6, the malloc call took about