diff --git a/toolkit/components/extensions/Schemas.jsm b/toolkit/components/extensions/Schemas.jsm
index b39ac38f3203..eaed6f193dd1 100644
--- a/toolkit/components/extensions/Schemas.jsm
+++ b/toolkit/components/extensions/Schemas.jsm
@@ -1187,7 +1187,7 @@ class Type extends Entry {
     }
 
     let choice;
-    if (/^[aeiou]/.test(type)) {
+    if ("aeiou".includes(type[0])) {
       choice = `be an ${type} value`;
     } else {
       choice = `be a ${type} value`;