--- a/implementation.js	Sun Jun 19 10:15:13 2011 -0600
+++ b/implementation.js	Sun Jun 19 10:37:45 2011 -0600
@@ -498,6 +498,10 @@
 		return;
 	}
 
+	if (!(command in commands)) {
+		return;
+	}
+
 	commands[command].action(value);
 
 	globalRange = null;
@@ -516,6 +520,10 @@
 		return;
 	}
 
+	if (!(command in commands)) {
+		return;
+	}
+
 	return commands[command].state();
 
 	globalRange = null;
@@ -534,6 +542,10 @@
 		return;
 	}
 
+	if (!(command in commands)) {
+		return;
+	}
+
 	return commands[command].value();
 
 	globalRange = null;