diff --git a/demo/demo.c b/demo/demo.c
index c5783bf..1301a86 100644
--- a/demo/demo.c
+++ b/demo/demo.c
@@ -50,6 +50,7 @@ static char helptext[][80] = {
 #include <fcntl.h>
 #include <err.h>
 #include <limits.h>
+#include <alloca.h>