diff --git a/include/git2/odb_backend.h b/include/git2/odb_backend.h
index af1e3e5b9..d004238a4 100644
--- a/include/git2/odb_backend.h
+++ b/include/git2/odb_backend.h
@@ -65,10 +65,13 @@ typedef enum {
 	GIT_STREAM_RW = (GIT_STREAM_RDONLY | GIT_STREAM_WRONLY),
 } git_odb_stream_t;
 
+typedef struct git_hash_ctx git_hash_ctx;
+
 /** A stream to read/write from a backend */
 struct git_odb_stream {
 	git_odb_backend *backend;
 	unsigned int mode;
+	git_hash_ctx *hash_ctx;
 
 	int (*read)(git_odb_stream *stream, char *buffer, size_t len);
 	int (*write)(git_odb_stream *stream, const char *buffer, size_t len);
diff --git a/src/odb.c b/src/odb.c
index 158159662..b7f64dfc9 100644
--- a/src/odb.c
+++ b/src/odb.c
@@ -871,11 +871,21 @@ int git_odb_write(
 	return error;
 }
 
+static void hash_header(git_hash_ctx *ctx, size_t size, git_otype type)
+{
+	char header[64];
+	int hdrlen;
+
+	hdrlen = git_odb__format_object_header(header, sizeof(header), size, type);
+	git_hash_update(ctx, header, hdrlen);
+}
+
 int git_odb_open_wstream(
 	git_odb_stream **stream, git_odb *db, size_t size, git_otype type)
 {
 	size_t i, writes = 0;
 	int error = GIT_ERROR;
+	git_hash_ctx *ctx;
 
 	assert(stream && db);
 
@@ -901,16 +911,26 @@ int git_odb_open_wstream(
 	if (error < 0 && !writes)
 		error = git_odb__error_unsupported_in_backend("write object");
 
+	ctx = git__malloc(sizeof(git_hash_ctx));
+	GITERR_CHECK_ALLOC(ctx);
+
+
+	git_hash_ctx_init(ctx);
+	hash_header(ctx, size, type);
+	(*stream)->hash_ctx = ctx;
+
 	return error;
 }
 
 int git_odb_stream_write(git_odb_stream *stream, const char *buffer, size_t len)
 {
+	git_hash_update(stream->hash_ctx, buffer, len);
 	return stream->write(stream, buffer, len);
 }
 
 int git_odb_stream_finalize_write(git_oid *out, git_odb_stream *stream)
 {
+	git_hash_final(out, stream->hash_ctx);
 	return stream->finalize_write(out, stream);
 }
 
@@ -921,6 +941,7 @@ int git_odb_stream_read(git_odb_stream *stream, char *buffer, size_t len)
 
 void git_odb_stream_free(git_odb_stream *stream)
 {
+	git__free(stream->hash_ctx);
 	stream->free(stream);
 }
 
diff --git a/src/odb_loose.c b/src/odb_loose.c
index 76ed8e232..a0c2c8c4c 100644
--- a/src/odb_loose.c
+++ b/src/odb_loose.c
@@ -776,8 +776,7 @@ static int loose_backend__stream_fwrite(git_oid *oid, git_odb_stream *_stream)
 	git_buf final_path = GIT_BUF_INIT;
 	int error = 0;
 
-	if (git_filebuf_hash(oid, &stream->fbuf) < 0 ||
-		object_file_name(&final_path, backend, oid) < 0 ||
+	if (object_file_name(&final_path, backend, oid) < 0 ||
 		object_mkdir(&final_path, backend) < 0)
 		error = -1;
 	/*
@@ -848,7 +847,6 @@ static int loose_backend__stream(git_odb_stream **stream_out, git_odb_backend *_
 
 	if (git_buf_joinpath(&tmp_path, backend->objects_dir, "tmp_object") < 0 ||
 		git_filebuf_open(&stream->fbuf, tmp_path.ptr,
-			GIT_FILEBUF_HASH_CONTENTS |
 			GIT_FILEBUF_TEMPORARY |
 			(backend->object_zlib_level << GIT_FILEBUF_DEFLATE_SHIFT)) < 0 ||
 		stream->stream.write((git_odb_stream *)stream, hdr, hdrlen) < 0)