diff --git a/tests/lib/wasmFetchPolyfill.mjs b/tests/lib/wasmFetchPolyfill.mjs
new file mode 100644
index 00000000..6ec6308d
--- /dev/null
+++ b/tests/lib/wasmFetchPolyfill.mjs
@@ -0,0 +1,29 @@
+/**
+ * Polyfill for Node.js 22+ where globalThis.fetch is built-in but rejects
+ * bare filesystem paths. WASM libraries like argon2-browser call fetch() with
+ * an absolute path (e.g. "/path/to/argon2.wasm") expecting a browser-style
+ * fallback, but Node.js 22's fetch throws synchronously for non-URL strings.
+ *
+ * This wrapper intercepts such calls and serves the file via Node's fs module,
+ * returning a synthetic Response so the WASM module loads correctly.
+ */
+
+import { readFile } from "fs/promises";
+
+if (globalThis.fetch) {
+    const originalFetch = globalThis.fetch;
+    globalThis.fetch = async function patchedFetch(url, options) {
+        const urlStr = typeof url === "string" ? url
+            : url instanceof URL ? url.href
+            : String(url);
+        // Intercept bare filesystem paths (absolute POSIX or Windows)
+        if (urlStr.startsWith("/") || /^[A-Za-z]:[/\\]/.test(urlStr)) {
+            const buffer = await readFile(urlStr);
+            return new Response(buffer, {
+                status: 200,
+                headers: { "Content-Type": "application/wasm" },
+            });
+        }
+        return originalFetch(url, options);
+    };
+}
diff --git a/tests/operations/index.mjs b/tests/operations/index.mjs
index bb81d32e..b25a2c2c 100644
--- a/tests/operations/index.mjs
+++ b/tests/operations/index.mjs
@@ -11,6 +11,7 @@
  * @license Apache-2.0
  */
 
+import "../lib/wasmFetchPolyfill.mjs";
 import { setLongTestFailure, logTestReport } from "../lib/utils.mjs";
 
 import TestRegister from "../lib/TestRegister.mjs";