diff --git a/hash.c b/hash.c
index 55d1d41770..b1296f0018 100644
--- a/hash.c
+++ b/hash.c
@@ -285,6 +285,7 @@ void git_hash_free(struct git_hash_ctx *ctx)
 void git_hash_init(struct git_hash_ctx *ctx, const struct git_hash_algo *algop)
 {
 	algop->init_fn(ctx);
+	ctx->active = true;
 }
 
 void git_hash_clone(struct git_hash_ctx *dst, const struct git_hash_ctx *src)
@@ -300,16 +301,21 @@ 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)
 {
 	ctx->algop->final_fn(hash, ctx);
+	ctx->active = false;
 }
 
 void git_hash_final_oid(struct object_id *oid, struct git_hash_ctx *ctx)
 {
 	ctx->algop->final_oid_fn(oid, ctx);
+	ctx->active = false;
 }
 
 void git_hash_discard(struct git_hash_ctx *ctx)
 {
+	if (!ctx->active)
+		return;
 	ctx->algop->discard_fn(ctx);
+	ctx->active = false;
 }
 
 uint32_t hash_algo_by_name(const char *name)
diff --git a/hash.h b/hash.h
index 121ecf13aa..cf94ad5700 100644
--- a/hash.h
+++ b/hash.h
@@ -281,6 +281,7 @@ struct git_hash_ctx {
 		git_SHA_CTX_unsafe sha1_unsafe;
 		git_SHA256_CTX sha256;
 	} state;
+	bool active;
 };
 
 typedef void (*git_hash_init_fn)(struct git_hash_ctx *ctx);