diff --git a/lib/modules/Standards.pmod/ASN1.pmod/Types.pmod b/lib/modules/Standards.pmod/ASN1.pmod/Types.pmod
index 41f098c961dd2f01726e194ea2bf41af8b0d51c6..07d430ea742b9379be7f78c6c6b6c235140a59f5 100644
--- a/lib/modules/Standards.pmod/ASN1.pmod/Types.pmod
+++ b/lib/modules/Standards.pmod/ASN1.pmod/Types.pmod
@@ -3,6 +3,8 @@
  * Encodes various asn.1 objects according to the Distinguished
  * Encoding Rules (DER) */
 
+#if constant(Gmp.mpz)
+
 #if 0
 #define WERROR werror
 #else
@@ -1107,3 +1109,5 @@ class meta_explicit
       valid_types = types;
     }
 }
+
+#endif /* Gmp.mpz */
\ No newline at end of file