diff --git a/skeletons/NULL.h b/skeletons/NULL.h
index 28a3630..7126e1d 100644
--- a/skeletons/NULL.h
+++ b/skeletons/NULL.h
@@ -23,6 +23,7 @@
 der_type_encoder_f NULL_encode_der;
 xer_type_decoder_f NULL_decode_xer;
 xer_type_encoder_f NULL_encode_xer;
+per_type_decoder_f NULL_decode_uper;
 
 #ifdef __cplusplus
 }