diff --git a/lib/plist.c b/lib/plist.c
index 1bb8bcd0..9eb6ab64 100644
--- a/lib/plist.c
+++ b/lib/plist.c
@@ -98,7 +98,7 @@ xbps_array_foreach_cb_multi(struct xbps_handle *xhp,
 		return 0;
 
 	maxthreads = (int)sysconf(_SC_NPROCESSORS_ONLN);
-	if (maxthreads == 1) /* use single threaded routine */
+	if (maxthreads < 0 || maxthreads == 1) /* use single threaded routine */
 		return xbps_array_foreach_cb(xhp, array, dict, fn, arg);
 
 	thd = calloc(maxthreads, sizeof(*thd));