diff --git a/packages/mermaid/src/diagrams/class/classDiagramGrammar.spec.ts b/packages/mermaid/src/diagrams/class/classDiagramGrammar.spec.ts
index eae09603f..0d6fe200c 100644
--- a/packages/mermaid/src/diagrams/class/classDiagramGrammar.spec.ts
+++ b/packages/mermaid/src/diagrams/class/classDiagramGrammar.spec.ts
@@ -1,10 +1,10 @@
 import { readFile } from 'node:fs/promises';
+import { fileURLToPath } from 'node:url';
 // @ts-ignore - no types
 import { LALRGenerator } from 'jison';
-import path from 'path';
 
 const getAbsolutePath = (relativePath: string) => {
-  return new URL(path.join(__dirname, relativePath)).pathname;
+  return fileURLToPath(new URL(relativePath, import.meta.url));
 };
 
 describe('class diagram grammar', function () {