diff --git a/refs/files-backend.c b/refs/files-backend.c
index eb14d12..0c3138e 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1,5 +1,6 @@
 #include "../cache.h"
 #include "../config.h"
+#include "../environment.h"
 #include "../gettext.h"
 #include "../hex.h"
 #include "../refs.h"