diff --git a/examples/xnf_add.vl b/examples/xnf_add.vl
index 012cc2206..08782db2f 100644
--- a/examples/xnf_add.vl
+++ b/examples/xnf_add.vl
@@ -25,7 +25,7 @@
  *
  * To compile this for XNF, try a command like this:
  *
- *    verilog -X -fpart=XC4010XLPQ160 -fncf=xnf_add.ncf xnf_add.v
+ *    iverilog -txnf -fpart=XC4010XLPQ160 -fncf=xnf_add.ncf xnf_add.v
  *
  * That command causes an xnf_add.xnf and xnf_add.ncf file to be created.
  * Next, make the xnf_add.ngd file with the command: