Index: uspace/srv/fs/fat/fat_ops.c
===================================================================
--- uspace/srv/fs/fat/fat_ops.c	(revision b6035ba00e0a19771a358284e5898b29f583e98f)
+++ uspace/srv/fs/fat/fat_ops.c	(revision 770d2816c8e85c4d0901dc1b8cf8f009dde36ffc)
@@ -552,4 +552,7 @@
 	uint16_t bps;
 	block_t *b;
+
+	if (!parentp)
+		return EBUSY;
 
 	futex_down(&parentp->lock);