diff --git a/web/src/getContrastYIQ.ts b/web/src/getContrastYIQ.ts
index 2d0b214..48e715f 100644
--- a/web/src/getContrastYIQ.ts
+++ b/web/src/getContrastYIQ.ts
@@ -13,9 +13,9 @@ export function getContrastYIQ(hexcolor: string) {
   }
 
   // Parse RGB values
-  const r = parseInt(hexcolor.substr(0, 2), 16);
-  const g = parseInt(hexcolor.substr(2, 2), 16);
-  const b = parseInt(hexcolor.substr(4, 2), 16);
+  const r = parseInt(hexcolor.substring(0, 2), 16);
+  const g = parseInt(hexcolor.substring(2, 2), 16);
+  const b = parseInt(hexcolor.substring(4, 2), 16);
 
   // Calculate YIQ brightness
   const yiq = (r * 299 + g * 587 + b * 114) / 1000;