diff --git a/packages/mondo/mondo.mjs b/packages/mondo/mondo.mjs
index bed568661..be7b2a203 100644
--- a/packages/mondo/mondo.mjs
+++ b/packages/mondo/mondo.mjs
@@ -8,6 +8,7 @@ This program is free software: you can redistribute it and/or modify it under th
 export class MondoParser {
   // these are the tokens we expect
   token_types = {
+    comment: /^\/\/(.*?)(?=\n|$)/,
     quotes_double: /^"(.*?)"/,
     quotes_single: /^'(.*?)'/,
     open_list: /^\(/,
@@ -428,7 +429,9 @@ export class MondoRunner {
   }
   evaluate_list(ast, scope) {
     // evaluate all children before evaluating list (dont mutate!!!)
-    const args = ast.children.map((arg) => this.evaluate(arg, scope));
+    const args = ast.children
+      .filter((child) => child.type !== 'comment') // ignore comments
+      .map((arg) => this.evaluate(arg, scope));
     const node = { type: 'list', children: args };
     return this.evaluator(node, scope);
   }
diff --git a/packages/mondo/test/mondo.test.mjs b/packages/mondo/test/mondo.test.mjs
index 4ec18decb..6e9260f08 100644
--- a/packages/mondo/test/mondo.test.mjs
+++ b/packages/mondo/test/mondo.test.mjs
@@ -67,6 +67,14 @@ describe('mondo s-expressions parser', () => {
         { type: 'number', value: '22.3' },
       ],
     }));
+  it('should parse comments', () =>
+    expect(p('a // hello')).toEqual({
+      type: 'list',
+      children: [
+        { type: 'plain', value: 'a' },
+        { type: 'comment', value: '// hello' },
+      ],
+    }));
 });
 
 let desguar = (a) => {