diff --git a/src/libravatarserv.cpp b/src/libravatarserv.cpp
index c016cff..eae2aa0 100644
--- a/src/libravatarserv.cpp
+++ b/src/libravatarserv.cpp
@@ -15,7 +15,8 @@
  */
 
 #include <iostream>
-#include <cstdlib>  // getenv()
+#include <algorithm>
+#include <cstdlib>
 #include <basedir.h>
 #include "libravatarserv.hpp"