diff --git a/grub-core/osdep/devmapper/getroot.c b/grub-core/osdep/devmapper/getroot.c
index 72e558275..a13a39c96 100644
--- a/grub-core/osdep/devmapper/getroot.c
+++ b/grub-core/osdep/devmapper/getroot.c
@@ -143,7 +143,7 @@ grub_util_get_dm_abstraction (const char *os_dev)
       grub_free (uuid);
       return GRUB_DEV_ABSTRACTION_LVM;
     }
-  if (strncmp (uuid, "CRYPT-LUKS1-", 4) == 0)
+  if (strncmp (uuid, "CRYPT-LUKS1-", 12) == 0)
     {
       grub_free (uuid);
       return GRUB_DEV_ABSTRACTION_LUKS;