diff --git a/src/Banner.js b/src/Banner.js
index 0b0832f..6c1856c 100644
--- a/src/Banner.js
+++ b/src/Banner.js
@@ -218,7 +218,7 @@ export default function Banner() {
                 <div className="banner-right-item">
                   <a
                     href="https://github.com/jaredreich/calcutext"
-                    rel="noreferrer"
+                    rel="noopener noreferrer"
                     target="_blank"
                   >
                     <img src={iconGitHub(COLOR_GRAY)} alt="GitHub" />
diff --git a/src/TextArea.js b/src/TextArea.js
index ac6f565..523c2b3 100644
--- a/src/TextArea.js
+++ b/src/TextArea.js
@@ -68,6 +68,10 @@ export default function App() {
 
   const getResultFromInput = ({ input, parser }) => {
     try {
+      // Pre-parse input
+      // Used to ignore underscores in numbers to enable rust-like syntax
+      input = input.replace(/\b([\d_]+)/gi, (match) => (match.replace(/_/gi,'')));
+
       const result = parser.evaluate(input);
 
       if (typeof result === 'number') {