diff --git a/cache.h b/cache.h
index 42f2f2754b93ff9d93883529778190d35a8ea43a..099a32e5fc536830fadc31cc68663ac3495a2a61 100644
--- a/cache.h
+++ b/cache.h
@@ -739,6 +739,7 @@ extern unsigned char* use_pack(struct packed_git *, struct pack_window **, off_t
 extern void close_pack_windows(struct packed_git *);
 extern void unuse_pack(struct pack_window **);
 extern void free_pack_by_name(const char *);
+extern void clear_delta_base_cache(void);
 extern struct packed_git *add_packed_git(const char *, int, int);
 extern const unsigned char *nth_packed_object_sha1(struct packed_git *, uint32_t);
 extern off_t nth_packed_object_offset(const struct packed_git *, uint32_t);
diff --git a/fast-import.c b/fast-import.c
index 6d5ee6f4636747d62abd06ae7a37dad8681beacc..5bc9ce2cc944d12914df0802fb4e010b056ed634 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -943,6 +943,7 @@ static void end_packfile(void)
 {
 	struct packed_git *old_p = pack_data, *new_p;
 
+	clear_delta_base_cache();
 	if (object_count) {
 		char *idx_name;
 		int i;
diff --git a/sha1_file.c b/sha1_file.c
index 0cfea9edc15402a38bbd195104c54e103b05f5a9..cbcae24d28f7000d2e55c4a2ef95026f07c5e5cc 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1630,6 +1630,13 @@ static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
 	}
 }
 
+void clear_delta_base_cache(void)
+{
+	unsigned long p;
+	for (p = 0; p < MAX_DELTA_CACHE; p++)
+		release_delta_base_cache(&delta_base_cache[p]);
+}
+
 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
 	void *base, unsigned long base_size, enum object_type type)
 {