diff -r a3b162331cd1 src/lib-storage/index/dbox-single/sdbox-file.c
--- a/src/lib-storage/index/dbox-single/sdbox-file.c	Tue Mar 13 17:01:56 2012 +0200
+++ b/src/lib-storage/index/dbox-single/sdbox-file.c	Tue Mar 13 17:12:09 2012 +0200
@@ -55,11 +55,11 @@
 	return &file->file;
 }
 
-struct dbox_file *sdbox_file_create(struct sdbox_mailbox *mbox)
+struct dbox_file *sdbox_file_create(struct sdbox_mailbox *mbox, uint32_t uid)
 {
 	struct dbox_file *file;
 
-	file = sdbox_file_init(mbox, 0);
+	file = sdbox_file_init(mbox, uid);
 	file->created = TRUE;
 	file->fd = file->storage->v.
 		file_create_fd(file, file->primary_path, FALSE);
diff -r a3b162331cd1 src/lib-storage/index/dbox-single/sdbox-file.h
--- a/src/lib-storage/index/dbox-single/sdbox-file.h	Tue Mar 13 17:01:56 2012 +0200
+++ b/src/lib-storage/index/dbox-single/sdbox-file.h	Tue Mar 13 17:12:09 2012 +0200
@@ -16,7 +16,7 @@
 };
 
 struct dbox_file *sdbox_file_init(struct sdbox_mailbox *mbox, uint32_t uid);
-struct dbox_file *sdbox_file_create(struct sdbox_mailbox *mbox);
+struct dbox_file *sdbox_file_create(struct sdbox_mailbox *mbox, uint32_t uid);
 void sdbox_file_free(struct dbox_file *file);
 
 /* Get file's extrefs metadata. */
diff -r a3b162331cd1 src/lib-storage/index/dbox-single/sdbox-save.c
--- a/src/lib-storage/index/dbox-single/sdbox-save.c	Tue Mar 13 17:01:56 2012 +0200
+++ b/src/lib-storage/index/dbox-single/sdbox-save.c	Tue Mar 13 17:12:09 2012 +0200
@@ -90,7 +90,7 @@
 	struct dbox_file *file;
 	int ret;
 
-	file = sdbox_file_create(ctx->mbox);
+	file = sdbox_file_create(ctx->mbox, _ctx->uid);
 	ctx->append_ctx = dbox_file_append_init(file);
 	ret = dbox_file_get_append_stream(ctx->append_ctx,
 					  &ctx->ctx.dbox_output);
@@ -233,8 +233,12 @@
 
 		ret = seq_range_array_iter_nth(&iter, n++, &uid);
 		i_assert(ret);
-		if (sdbox_file_assign_uid(sfile, uid) < 0)
-			return -1;
+		if (sfile->uid != 0) {
+			i_assert(sfile->uid == uid);
+		} else {
+			if (sdbox_file_assign_uid(sfile, uid) < 0)
+				return -1;
+		}
 	}
 	i_assert(!seq_range_array_iter_nth(&iter, n, &uid));
 	return 0;