diff --git a/config.h.in b/config.h.in
index 5c2ac37..b1b711f 100644
--- a/config.h.in
+++ b/config.h.in
@@ -225,6 +225,9 @@
 /* Define if you want to use BSD db. */
 #undef WITH_LIBDB
 
+/* Define if you want to use ndbm. */
+#undef WITH_LIBNDBM
+
 /* Define if you want to produce an OpenStep/Rhapsody framework
    (shared library plus accessory files). */
 #undef WITH_NEXT_FRAMEWORK