diff --git a/listings/globals/arguments-status-code.js b/listings/globals/arguments-status-code.js
index 5682fa3..b9edb19 100644
--- a/listings/globals/arguments-status-code.js
+++ b/listings/globals/arguments-status-code.js
@@ -19,6 +19,8 @@ function readFile(file) {
 
 if (process.argv.length > 0) {
   process.argv.forEach(function(arg, index) {
-    args[arg].apply(this, process.argv.slice(index + 1));
+    if (args[arg]) {
+      args[arg].apply(this, process.argv.slice(index + 1));
+    }
   });
 }
diff --git a/listings/globals/bad-nexttick.js b/listings/globals/bad-nexttick.js
index 08add18..4641137 100644
--- a/listings/globals/bad-nexttick.js
+++ b/listings/globals/bad-nexttick.js
@@ -3,7 +3,7 @@ var EventEmitter = require('events').EventEmitter;
 function complexOperations() {
   var events = new EventEmitter();
 
-  events.emit('success'); <co id="callout-globals-nexttick-1"/>
+  events.emit('success'); //<co id="callout-globals-nexttick-1"/>
 
   return events;
 }
diff --git a/listings/globals/nexttick.js b/listings/globals/nexttick.js
index 8bebff3..0a7ebcf 100644
--- a/listings/globals/nexttick.js
+++ b/listings/globals/nexttick.js
@@ -3,7 +3,7 @@ var EventEmitter = require('events').EventEmitter;
 function complexOperations() {
   var events = new EventEmitter();
 
-  process.nextTick(function() { <co id="callout-globals-nexttick-2"/>
+  process.nextTick(function() { //<co id="callout-globals-nexttick-2"/>
     events.emit('success');
   });