Index: uspace/srv/vfs/vfs_file.c
===================================================================
--- uspace/srv/vfs/vfs_file.c	(revision 28a3e74e6d058abea15c330564b3724616fe271b)
+++ uspace/srv/vfs/vfs_file.c	(revision 6639ae1d13d082109687b0dffeb0af25085f9f7c)
@@ -258,7 +258,9 @@
 	if ((fd >= 0) && (fd < MAX_OPEN_FILES)) {
 		vfs_file_t *file = FILES[fd];
-		vfs_file_addref(file);
-		fibril_mutex_unlock(&VFS_DATA->lock);
-		return file;
+		if (file != NULL) {
+			vfs_file_addref(file);
+			fibril_mutex_unlock(&VFS_DATA->lock);
+			return file;
+		}
 	}
 	fibril_mutex_unlock(&VFS_DATA->lock);