diff --git a/lib/autoconf/status.m4 b/lib/autoconf/status.m4
index 8afa9ba..6dd29b5 100644
--- a/lib/autoconf/status.m4
+++ b/lib/autoconf/status.m4
@@ -816,7 +816,9 @@ cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
   if (D_is_set[macro]) {
     # Preserve the white space surrounding the "#".
     prefix = substr(line, 1, index(line, defundef) - 1)
+    print prefix "ifndef", macro
     print prefix "define", macro P[macro] D[macro]
+    print prefix "endif"
     next
   } else {
     # Replace #undef with comments.  This is necessary, for example,