diff --git a/include/ntfs-3g/endians.h b/include/ntfs-3g/endians.h
index 0be0a8f7..a010b1a2 100644
--- a/include/ntfs-3g/endians.h
+++ b/include/ntfs-3g/endians.h
@@ -318,4 +318,6 @@
 
 #define sle64_cmpz(a) (!(a))
 
+#define be16_cmpz(a) (!(a))
+
 #endif /* defined _NTFS_ENDIANS_H */
diff --git a/libntfs-3g/security.c b/libntfs-3g/security.c
index c8ed0969..1c34546c 100644
--- a/libntfs-3g/security.c
+++ b/libntfs-3g/security.c
@@ -243,7 +243,7 @@ int ntfs_sid_to_mbs_size(const SID *sid)
 	 * maximum is 2^32-1 = 4294967295 = 10 characters.  If it needs to be
 	 * in hexadecimal, then maximum is 0x665544332211 = 14 characters.
 	 */
-	if (!sid->identifier_authority.high_part)
+	if (be16_cmpz(sid->identifier_authority.high_part))
 		size += 10;
 	else
 		size += 14;
@@ -326,7 +326,7 @@ char *ntfs_sid_to_mbs(const SID *sid, char *sid_str, size_t sid_str_size)
 	/* Add the identifier authority. */
 	for (u = i = 0, j = 40; i < 6; i++, j -= 8)
 		u += (u64)sid->identifier_authority.value[i] << j;
-	if (!sid->identifier_authority.high_part)
+	if (be16_cmpz(sid->identifier_authority.high_part))
 		i = snprintf(s, cnt, "%lu", (unsigned long)u);
 	else
 		i = snprintf(s, cnt, "0x%llx", (unsigned long long)u);