diff --git a/sparse-index.c b/sparse-index.c
index fdae901..8860547 100644
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "alloc.h"
+#include "environment.h"
 #include "gettext.h"
 #include "repository.h"
 #include "sparse-index.h"