diff --git a/Documentation/technical/api-hashmap.txt b/Documentation/technical/api-hashmap.txt
index 28f5a8b715..a3f020cd9e 100644
--- a/Documentation/technical/api-hashmap.txt
+++ b/Documentation/technical/api-hashmap.txt
@@ -188,7 +188,9 @@ Returns the removed entry, or NULL if not found.
 `void *hashmap_iter_next(struct hashmap_iter *iter)`::
 `void *hashmap_iter_first(struct hashmap *map, struct hashmap_iter *iter)`::
 
-	Used to iterate over all entries of a hashmap.
+	Used to iterate over all entries of a hashmap. Note that it is
+	not safe to add or remove entries to the hashmap while
+	iterating.
 +
 `hashmap_iter_init` initializes a `hashmap_iter` structure.
 +
diff --git a/sha1_file.c b/sha1_file.c
index 1173071859..7827f4e90f 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -2350,11 +2350,10 @@ static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
 
 void clear_delta_base_cache(void)
 {
-	struct hashmap_iter iter;
-	struct delta_base_cache_entry *entry;
-	for (entry = hashmap_iter_first(&delta_base_cache, &iter);
-	     entry;
-	     entry = hashmap_iter_next(&iter)) {
+	struct list_head *lru, *tmp;
+	list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
+		struct delta_base_cache_entry *entry =
+			list_entry(lru, struct delta_base_cache_entry, lru);
 		release_delta_base_cache(entry);
 	}
 }