diff --git a/grub-core/osdep/linux/ofpath.c b/grub-core/osdep/linux/ofpath.c
index 0ebfea44c..38d9bb5bf 100644
--- a/grub-core/osdep/linux/ofpath.c
+++ b/grub-core/osdep/linux/ofpath.c
@@ -507,7 +507,7 @@ check_sas (const char *sysfs_path, int *tgt, unsigned long int *sas_address)
   p_len = (int) (q - sysfs_path);
   ed_len = (int) (q - ed);
 
-  path_size = (p_len + ed_len + sizeof ("%s/sas_device/%s/phy_identifier"));
+  path_size = (p_len + ed_len + sizeof ("/sas_device//phy_identifier"));
   path = xmalloc (path_size);
   snprintf (path, path_size, "%.*s/sas_device/%.*s/phy_identifier", p_len,
 	    sysfs_path, ed_len, ed);