diff --git a/common.cpp b/common.cpp
index 2c12e94..9c292e2 100644
--- a/common.cpp
+++ b/common.cpp
@@ -1,5 +1,6 @@
 #include "common.h"
 
+#include <algorithm>
 #include <vector>
 
 const int HIST_MAX = 20;