diff --git a/src/main.cc b/src/main.cc
index b0b93edb..40fee26b 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -29,6 +29,7 @@
 #include "clock.hh"
 
 #include <fcntl.h>
+#include <locale.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>