-extern int nd_push_buffer(netdissect_options *, u_char *, const u_char *,
- u_int);
-extern int nd_push_snaplen(netdissect_options *, const u_char *, u_int);
-extern void nd_change_snaplen(netdissect_options *, const u_char *, u_int);
+extern WARN_UNUSED_RESULT int nd_push_buffer(netdissect_options *, u_char *, const u_char *, const u_int);
+extern WARN_UNUSED_RESULT int nd_push_snaplen(netdissect_options *, const u_char *, const u_int);
+extern void nd_change_snaplen(netdissect_options *, const u_char *, const u_int);