Index: uspace/lib/fs/libfs.c
===================================================================
--- uspace/lib/fs/libfs.c	(revision 6aae539df68d767b7b3864f2cd3ae3398af9dde1)
+++ uspace/lib/fs/libfs.c	(revision 6eef3c4403b57fc01e6b79237e6cc0a6a6a7d016)
@@ -339,5 +339,5 @@
 	 */
 	rc = async_share_in_start_0_0(exch, PLB_SIZE, (void *) &reg.plb_ro);
-	if (reg.plb_ro == (void *) -1) {
+	if (reg.plb_ro == AS_MAP_FAILED) {
 		async_exchange_end(exch);
 		async_forget(req);