diff --git a/skeletons/NULL.h b/skeletons/NULL.h
index 7126e1d..131e775 100644
--- a/skeletons/NULL.h
+++ b/skeletons/NULL.h
@@ -24,6 +24,7 @@
 xer_type_decoder_f NULL_decode_xer;
 xer_type_encoder_f NULL_encode_xer;
 per_type_decoder_f NULL_decode_uper;
+per_type_encoder_f NULL_encode_uper;
 
 #ifdef __cplusplus
 }