diff --git a/include/polarssl/config.h b/include/polarssl/config.h
index aa35af2..737e5b4 100644
--- a/include/polarssl/config.h
+++ b/include/polarssl/config.h
@@ -661,6 +661,17 @@
 #define POLARSSL_SSL_TRUNCATED_HMAC
 
 /**
+ * \def POLARSSL_X509_ALLOW_EXTENSIONS_NON_V3
+ *
+ * If set, the X509 parser will not break-off when parsing an X509 certificate
+ * and encountering an extension in a v1 or v2 certificate.
+ *
+ * Uncomment to prevent an error.
+ *
+#define POLARSSL_X509_ALLOW_EXTENSIONS_NON_V3
+ */
+
+/**
  * \def POLARSSL_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION
  *
  * If set, the X509 parser will not break-off when parsing an X509 certificate