1 files changed, 1 insertions, 0 deletions

diff --git a/option.cc b/option.cc
index af9c8a59..bc173e84 100644
--- a/option.cc
+++ b/option.cc
@@ -6,6 +6,7 @@
 
 #include <iostream>
 #include <cstdarg>
+#include <cstdlib>
 #include <unistd.h>
 
 #include "util.h"