diff --git a/mcopy.cpp b/mcopy.cpp
index 53ce670..42747a2 100644
--- a/mcopy.cpp
+++ b/mcopy.cpp
@@ -10,6 +10,7 @@
 #include <string>
 #include <fstream>
 #include <regex>
+#include <cstdlib>
 #include <tag.h>
 #include <fileref.h>