diff --git a/disk/part_efi.c b/disk/part_efi.c
index d6bb53e6b5..239455b816 100644
--- a/disk/part_efi.c
+++ b/disk/part_efi.c
@@ -66,7 +66,7 @@ static char *print_efiname(gpt_entry *pte)
 	return name;
 }
 
-static efi_guid_t system_guid = PARTITION_SYSTEM_GUID;
+static const efi_guid_t system_guid = PARTITION_SYSTEM_GUID;
 
 static inline int is_bootable(gpt_entry *p)
 {