diff --git a/src/main/PDFOperations.js b/src/main/PDFOperations.js
index a2494ba..b466921 100644
--- a/src/main/PDFOperations.js
+++ b/src/main/PDFOperations.js
@@ -441,10 +441,16 @@ async function loadPdfjs() {
 
 // Points pdfjs-dist at its bundled standard font metrics so it doesn't warn
 // (and degrade text-extraction fidelity) when a PDF uses a standard font.
+// pdfjs validates this as a URL that must end with a forward slash — a raw
+// Windows path (C:\...\standard_fonts\) fails that check and breaks
+// extractText/extractImages on Windows, so always hand pdfjs a file:// URL.
 function getStandardFontDataUrl() {
-  return (
-    path.join(path.dirname(require.resolve('pdfjs-dist/package.json')), 'standard_fonts') + path.sep
+  const dir = path.join(
+    path.dirname(require.resolve('pdfjs-dist/package.json')),
+    'standard_fonts'
   );
+  const url = require('url').pathToFileURL(dir);
+  return url.href.endsWith('/') ? url.href : url.href + '/';
 }
 
 async function pdfExtractText(data) {
diff --git a/tests/main/PDFBatchOperations.test.js b/tests/main/PDFBatchOperations.test.js
index f3c2c61..8eba832 100644
--- a/tests/main/PDFBatchOperations.test.js
+++ b/tests/main/PDFBatchOperations.test.js
@@ -293,7 +293,9 @@ describe('PDFBatchOperations - runPDFBatchOperation', () => {
         operation: 'compress',
         outputFolder: path.join(blocker, 'child'),
         data: {},
-        sanitizeError: (message) => message.replace(new RegExp(path.sep, 'g'), '_SANITIZED_'),
+        // path.sep is "\" on Windows — escape it for RegExp use
+        sanitizeError: (message) =>
+          message.replace(new RegExp(path.sep.replace(/\\/g, '\\\\'), 'g'), '_SANITIZED_'),
       });
 
       expect(completion.success).toBe(false);