Index: uspace/srv/fs/fat/fat_fat.c
===================================================================
--- uspace/srv/fs/fat/fat_fat.c	(revision 16fc3c94620219718099d4fa2d485a4c03e071a5)
+++ uspace/srv/fs/fat/fat_fat.c	(revision 5178ee2410163df7278162932c59d09a09e5a446)
@@ -147,4 +147,10 @@
 	fat_cluster_t lastc;
 	int rc;
+
+	/*
+	 * This function can only operate on non-zero length files.
+	 */
+	if (firstc == FAT_CLST_RES0)
+		return ELIMIT;
 
 	bps = uint16_t_le2host(bs->bps);