diff --git a/modules/module.vtt2ass.ts b/modules/module.vtt2ass.ts
index b85668d..dee43ce 100644
--- a/modules/module.vtt2ass.ts
+++ b/modules/module.vtt2ass.ts
@@ -126,6 +126,13 @@ function parseStyle(stylegroup: string, line: string, style: any) {
         break;
       }
       break;
+    case 'text-decoration':
+      if (st[1] === 'underline') {
+        style[8] = -1;
+      } else {
+        console.warn(`vtt2ass: Unknown text-decoration value: ${st[1]}`);
+      }
+      break;
     case 'font-style':
       if (st[1] === 'italic') {
         style[7] = -1;