diff --git a/include/portable.nt b/include/portable.nt
index e2769f98cd..f906abc7ae 100644
--- a/include/portable.nt
+++ b/include/portable.nt
@@ -435,7 +435,7 @@ typedef signed int ssize_t;
 /* #undef HAVE_SYSCONF */
 
 /* Define if you have the tempnam function.  */
-/* #undef HAVE_TEMPNAM */
+#define HAVE_TEMPNAM 1
 
 /* Define if you have the thr_getconcurrency function.  */
 /* #undef HAVE_THR_GETCONCURRENCY */