diff --git a/utf8.c b/utf8.c
index 6d80266b..c0407576 100644
--- a/utf8.c
+++ b/utf8.c
@@ -20,6 +20,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <wchar.h>
 
 #include "tmux.h"