diff --git a/src/shrpx_router.cc b/src/shrpx_router.cc
index 9b9f7b73..e0404252 100644
--- a/src/shrpx_router.cc
+++ b/src/shrpx_router.cc
@@ -24,6 +24,8 @@
  */
 #include "shrpx_router.h"
 
+#include <algorithm>
+
 #include "shrpx_config.h"
 
 namespace shrpx {