diff --git a/ext/web/10_filereader.js b/ext/web/10_filereader.js
index 56794d8b81..9df0086b48 100644
--- a/ext/web/10_filereader.js
+++ b/ext/web/10_filereader.js
@@ -367,7 +367,7 @@
     /** @param {Blob} blob */
     readAsDataURL(blob) {
       webidl.assertBranded(this, FileReader);
-      const prefix = "Failed to execute 'readAsBinaryString' on 'FileReader'";
+      const prefix = "Failed to execute 'readAsDataURL' on 'FileReader'";
       webidl.requiredArguments(arguments.length, 1, { prefix });
       // alias for readAsArrayBuffer
       this.#readOperation(blob, { kind: "DataUrl" });
@@ -379,7 +379,7 @@
      */
     readAsText(blob, encoding = undefined) {
       webidl.assertBranded(this, FileReader);
-      const prefix = "Failed to execute 'readAsBinaryString' on 'FileReader'";
+      const prefix = "Failed to execute 'readAsText' on 'FileReader'";
       webidl.requiredArguments(arguments.length, 1, { prefix });
       if (encoding !== undefined) {
         encoding = webidl.converters["DOMString"](encoding, {