diff --git a/read-cache.c b/read-cache.c
index 04ed561bfe7dd8fbf1988190f95eb1cc3530ff58..4245f8ef30bc740f97c278abdb9cc15e7017aa47 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1518,8 +1518,9 @@ int discard_index(struct index_state *istate)
 	free_name_hash(istate);
 	cache_tree_free(&(istate->cache_tree));
 	istate->initialized = 0;
-
-	/* no need to throw away allocated active_cache */
+	free(istate->cache);
+	istate->cache = NULL;
+	istate->cache_alloc = 0;
 	return 0;
 }