Index: uspace/lib/fs/libfs.c
===================================================================
--- uspace/lib/fs/libfs.c	(revision 7eb0fed89435279831404b521cf4bb3b30d02cd6)
+++ uspace/lib/fs/libfs.c	(revision 75aa59afaf341ef369f9275528ff77e04017f4f4)
@@ -157,6 +157,6 @@
 	rc = vfs_out_ops->write(devmap_handle, index, pos, &wbytes, &nsize);
 
-	if (rc == EOK)	// FIXME: nsize is 64-bit
-		async_answer_2(rid, EOK, wbytes, nsize);
+	if (rc == EOK)
+		async_answer_3(rid, EOK, wbytes, LOWER32(nsize), UPPER32(nsize));
 	else
 		async_answer_0(rid, rc);