diff --git a/hash.c b/hash.c
index e925b9754e..63672a3d22 100644
--- a/hash.c
+++ b/hash.c
@@ -283,6 +283,18 @@ void git_hash_final_oid(struct object_id *oid, struct git_hash_ctx *ctx)
 	ctx->algop->final_oid_fn(oid, ctx);
 }
 
+void git_hash_discard(struct git_hash_ctx *ctx)
+{
+	/*
+	 * XXX Many implementations do not need to do anything here,
+	 * and a dummy final() call is wasteful. But we can't fix
+	 * that unless our implementation API exposes a discard
+	 * primitive.
+	 */
+	unsigned char dummy[GIT_MAX_RAWSZ];
+	git_hash_final(dummy, ctx);
+}
+
 uint32_t hash_algo_by_name(const char *name)
 {
 	if (!name)
diff --git a/hash.h b/hash.h
index c082a53c9a..6b2f04e2a4 100644
--- a/hash.h
+++ b/hash.h
@@ -325,6 +325,7 @@ void git_hash_clone(struct git_hash_ctx *dst, const struct git_hash_ctx *src);
 void git_hash_update(struct git_hash_ctx *ctx, const void *in, size_t len);
 void git_hash_final(unsigned char *hash, struct git_hash_ctx *ctx);
 void git_hash_final_oid(struct object_id *oid, struct git_hash_ctx *ctx);
+void git_hash_discard(struct git_hash_ctx *ctx);
 const struct git_hash_algo *hash_algo_ptr_by_number(uint32_t algo);
 struct git_hash_ctx *git_hash_alloc(void);
 void git_hash_free(struct git_hash_ctx *ctx);