guard PER references
diff --git a/skeletons/BIT_STRING.c b/skeletons/BIT_STRING.c
index 7b8e975..e92f27e 100644
--- a/skeletons/BIT_STRING.c
+++ b/skeletons/BIT_STRING.c
@@ -27,8 +27,13 @@
OCTET_STRING_encode_der, /* Implemented in terms of OCTET STRING */
OCTET_STRING_decode_xer_binary,
BIT_STRING_encode_xer,
+#ifdef ASN_DISABLE_PER_SUPPORT
+ 0,
+ 0,
+#else
OCTET_STRING_decode_uper, /* Unaligned PER decoder */
OCTET_STRING_encode_uper, /* Unaligned PER encoder */
+#endif /* ASN_DISABLE_PER_SUPPORT */
0, /* Use generic outmost tag fetcher */
asn_DEF_BIT_STRING_tags,
sizeof(asn_DEF_BIT_STRING_tags)