diff --git a/bin/now-alias b/bin/now-alias
index 9ec1da1..b4c7d0b 100755
--- a/bin/now-alias
+++ b/bin/now-alias
@@ -103,22 +103,26 @@ async function run (token) {
   switch (subcommand) {
     case 'list':
     case 'ls':
-      await alias.ls(argv._[0]);
+      await alias.ls(null != argv._[0] ? String(argv._[0]) : null);
       break;
 
     case 'remove':
     case 'rm':
-      await alias.rm(argv._[0]);
+      await alias.rm(String(argv._[0]));
       break;
 
     case 'add':
     case 'set':
-      await alias.set(argv._[0], argv._[1]);
+      if (2 !== argv._.length) {
+        error('Invalid number of arguments');
+        return;
+      }
+      await alias.set(String(argv._[0]), String(argv._[1]));
       break;
 
     default:
       if (2 === argv._.length) {
-        await alias.set(argv._[0], argv._[1]);
+        await alias.set(String(argv._[0]), String(argv._[1]));
       } else if (argv._.length >= 3) {
         error('Invalid number of arguments');
         help();