diff --git a/builtin/fsck.c b/builtin/fsck.c
index d42a27da89..d9f4e6e38c 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -298,7 +298,7 @@ static int fsck_obj(struct object *obj)
 
 	if (fsck_walk(obj, mark_used, NULL))
 		objerror(obj, "broken links");
-	if (fsck_object(obj, check_strict, fsck_error_func))
+	if (fsck_object(obj, NULL, 0, check_strict, fsck_error_func))
 		return -1;
 
 	if (obj->type == OBJ_TREE) {
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 5568a5bc3b..f2465ff18e 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -773,7 +773,8 @@ static void sha1_object(const void *data, struct object_entry *obj_entry,
 			if (!obj)
 				die(_("invalid %s"), typename(type));
 			if (do_fsck_object &&
-			    fsck_object(obj, 1, fsck_error_function))
+			    fsck_object(obj, buf, size, 1,
+				    fsck_error_function))
 				die(_("Error in object"));
 			if (fsck_walk(obj, mark_link, NULL))
 				die(_("Not all child objects of %s are reachable"), sha1_to_hex(obj->sha1));
diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
index 99cde45879..855d94b90b 100644
--- a/builtin/unpack-objects.c
+++ b/builtin/unpack-objects.c
@@ -164,10 +164,10 @@ static unsigned nr_objects;
  * Called only from check_object() after it verified this object
  * is Ok.
  */
-static void write_cached_object(struct object *obj)
+static void write_cached_object(struct object *obj, struct obj_buffer *obj_buf)
 {
 	unsigned char sha1[20];
-	struct obj_buffer *obj_buf = lookup_object_buffer(obj);
+
 	if (write_sha1_file(obj_buf->buffer, obj_buf->size, typename(obj->type), sha1) < 0)
 		die("failed to write object %s", sha1_to_hex(obj->sha1));
 	obj->flags |= FLAG_WRITTEN;
@@ -180,6 +180,8 @@ static void write_cached_object(struct object *obj)
  */
 static int check_object(struct object *obj, int type, void *data)
 {
+	struct obj_buffer *obj_buf;
+
 	if (!obj)
 		return 1;
 
@@ -198,11 +200,15 @@ static int check_object(struct object *obj, int type, void *data)
 		return 0;
 	}
 
-	if (fsck_object(obj, 1, fsck_error_function))
+	obj_buf = lookup_object_buffer(obj);
+	if (!obj_buf)
+		die("Whoops! Cannot find object '%s'", sha1_to_hex(obj->sha1));
+	if (fsck_object(obj, obj_buf->buffer, obj_buf->size, 1,
+			fsck_error_function))
 		die("Error in object");
 	if (fsck_walk(obj, check_object, NULL))
 		die("Error on reachable objects of %s", sha1_to_hex(obj->sha1));
-	write_cached_object(obj);
+	write_cached_object(obj, obj_buf);
 	return 0;
 }
 
diff --git a/fsck.c b/fsck.c
index 56156fff44..dd77628958 100644
--- a/fsck.c
+++ b/fsck.c
@@ -277,7 +277,7 @@ static int fsck_ident(const char **ident, struct object *obj, fsck_error error_f
 }
 
 static int fsck_commit_buffer(struct commit *commit, const char *buffer,
-			      fsck_error error_func)
+	unsigned long size, fsck_error error_func)
 {
 	unsigned char tree_sha1[20], sha1[20];
 	struct commit_graft *graft;
@@ -322,15 +322,18 @@ static int fsck_commit_buffer(struct commit *commit, const char *buffer,
 	return 0;
 }
 
-static int fsck_commit(struct commit *commit, fsck_error error_func)
+static int fsck_commit(struct commit *commit, const char *data,
+	unsigned long size, fsck_error error_func)
 {
-	const char *buffer = get_commit_buffer(commit, NULL);
-	int ret = fsck_commit_buffer(commit, buffer, error_func);
-	unuse_commit_buffer(commit, buffer);
+	const char *buffer = data ?  data : get_commit_buffer(commit, &size);
+	int ret = fsck_commit_buffer(commit, buffer, size, error_func);
+	if (!data)
+		unuse_commit_buffer(commit, buffer);
 	return ret;
 }
 
-static int fsck_tag(struct tag *tag, fsck_error error_func)
+static int fsck_tag(struct tag *tag, const char *data,
+	unsigned long size, fsck_error error_func)
 {
 	struct object *tagged = tag->tagged;
 
@@ -339,7 +342,8 @@ static int fsck_tag(struct tag *tag, fsck_error error_func)
 	return 0;
 }
 
-int fsck_object(struct object *obj, int strict, fsck_error error_func)
+int fsck_object(struct object *obj, void *data, unsigned long size,
+	int strict, fsck_error error_func)
 {
 	if (!obj)
 		return error_func(obj, FSCK_ERROR, "no valid object to fsck");
@@ -349,9 +353,11 @@ int fsck_object(struct object *obj, int strict, fsck_error error_func)
 	if (obj->type == OBJ_TREE)
 		return fsck_tree((struct tree *) obj, strict, error_func);
 	if (obj->type == OBJ_COMMIT)
-		return fsck_commit((struct commit *) obj, error_func);
+		return fsck_commit((struct commit *) obj, (const char *) data,
+			size, error_func);
 	if (obj->type == OBJ_TAG)
-		return fsck_tag((struct tag *) obj, error_func);
+		return fsck_tag((struct tag *) obj, (const char *) data,
+			size, error_func);
 
 	return error_func(obj, FSCK_ERROR, "unknown type '%d' (internal fsck error)",
 			  obj->type);
diff --git a/fsck.h b/fsck.h
index 1e4f527318..d1e6387a44 100644
--- a/fsck.h
+++ b/fsck.h
@@ -28,6 +28,8 @@ int fsck_error_function(struct object *obj, int type, const char *fmt, ...);
  *    0		everything OK
  */
 int fsck_walk(struct object *obj, fsck_walk_func walk, void *data);
-int fsck_object(struct object *obj, int strict, fsck_error error_func);
+/* If NULL is passed for data, we assume the object is local and read it. */
+int fsck_object(struct object *obj, void *data, unsigned long size,
+	int strict, fsck_error error_func);
 
 #endif