diff --git a/src/config.in b/src/config.in
index 9e498ae69a4..0ab350f0abe 100644
--- a/src/config.in
+++ b/src/config.in
@@ -33,9 +33,12 @@ Boston, MA 02111-1307, USA.  */
    numbers. */
 #undef LISP_FLOAT_TYPE
 
-/* Define GNU_MALLOC if you want to use the *new* GNU memory allocator. */
+/* Define GNU_MALLOC if you want to use the GNU memory allocator. */
 #undef GNU_MALLOC
 
+/* Define if you are using the GNU C Library. */
+#undef DOUG_LEA_MALLOC
+
 /* Define REL_ALLOC if you want to use the relocating allocator for
    buffer space. */
 #undef REL_ALLOC