--- a/src/js/compat.ts
+++ b/src/js/compat.ts
@@ -192,9 +192,10 @@
 }
 
 export async function loadBinaryFile(
-  path: string,
+  path: string | Uint8Array,
   file_sub_resource_hash?: string | undefined,
 ): Promise<Uint8Array> {
+  if (path instanceof Uint8Array) return path;
   const { response, binary } = getBinaryResponse(path, file_sub_resource_hash);
   if (binary) {
     return binary;
--- a/src/js/emscripten-settings.ts
+++ b/src/js/emscripten-settings.ts
@@ -70,7 +70,7 @@
     // means dependency resolution has already failed and we want to throw an
     // error anyways.
     locateFile: (path: string) => config.indexURL + path,
-    instantiateWasm: getInstantiateWasmFunc(config.indexURL),
+    instantiateWasm: getInstantiateWasmFunc(config.indexURL, config.qlcWasmBytes),
   };
   return settings;
 }
@@ -146,7 +146,7 @@
  *
  * @param stdlibURL The URL for the Python standard library
  */
-function installStdlib(stdlibURL: string): PreRunFunc {
+function installStdlib(stdlibURL: string | Uint8Array): PreRunFunc {
   const stdlibPromise: Promise<Uint8Array> = loadBinaryFile(stdlibURL);
   return async (Module: PyodideModule) => {
     Module.API.pyVersionTuple = computeVersionTuple(Module);
@@ -197,6 +197,7 @@
 
 function getInstantiateWasmFunc(
   indexURL: string,
+  bytes?: Uint8Array,
 ): EmscriptenSettings["instantiateWasm"] {
   // @ts-ignore
   if (SOURCEMAP || typeof WasmOffsetConverter !== "undefined") {
@@ -207,9 +208,12 @@
     // https://emscripten.org/docs/api_reference/module.html?highlight=instantiatewasm#Module.instantiateWasm
     //
     // typeof WasmOffsetConverter !== "undefined" checks for asan.
-    return;
+    throw new Error("Unsupported debug build");
   }
-  const { binary, response } = getBinaryResponse(indexURL + "pyodide.asm.wasm");
+  if (!(bytes instanceof Uint8Array) || bytes.byteLength !== 9598218)
+    throw new Error("Missing pinned Wasm bytes");
+  const binary = Promise.resolve(bytes);
+  const response: undefined = undefined;
   const jsvErrorImportPromise = getJsvErrorImport();
   return function (
     imports: { [key: string]: { [key: string]: any } },
--- a/src/js/pyodide.ts
+++ b/src/js/pyodide.ts
@@ -108,7 +108,9 @@
    * file. This URL includes the most of the Python standard library.
    * Default: ```${indexURL}/python_stdlib.zip```
    */
-  stdLibURL?: string;
+  stdLibURL?: string | Uint8Array;
+  /** Verified Wasm input for the version-specific QLC loader adaptation. */
+  qlcWasmBytes?: Uint8Array;
   /**
    * Override the standard input callback. Should ask the user for one line of
    * input. The :js:func:`pyodide.setStdin` function is more flexible and