diff --git a/include/ldap_pvt.h b/include/ldap_pvt.h
index 042cdd18d938b248e49d733f520cc572cf7deea6..12eda79f1724af53478ec72bb4bec320c7c660a1 100644
--- a/include/ldap_pvt.h
+++ b/include/ldap_pvt.h
@@ -216,7 +216,7 @@ LDAP_F (char *) ldap_utf8_strpbrk( const char* str, const char *set);
 LDAP_F (char*) ldap_utf8_strtok( char* sp, const char* sep, char **last);
 
 /* Optimizations */
-#define LDAP_UTF8_ISASCII(p) ( * (const unsigned char *) (p) < 0x100 )
+#define LDAP_UTF8_ISASCII(p) ( * (const unsigned char *) (p) < 0x80 )
 #define LDAP_UTF8_CHARLEN(p) ( LDAP_UTF8_ISASCII(p) \
 	? 1 : ldap_utf8_charlen((p)) )
 #define LDAP_UTF8_OFFSET(p) ( LDAP_UTF8_ISASCII(p) \