diff --git a/docs/project/changelog.md b/docs/project/changelog.md
index 22d5ba5b9..effae95b3 100644
--- a/docs/project/changelog.md
+++ b/docs/project/changelog.md
@@ -67,6 +67,10 @@ substitutions:
   {pr}`3015` included in 0.21.2) and if there is a variable in top level scope
   called `__dirname` we use that for the `indexURL`.
 
+- {{ Fix }} `loadPyodide` will now raise error when the version of
+  JavaScript and Python Pyodide package does not match.
+  {pr}`3074`
+
 ### Build System / Package Loading
 
 - New packages: pycryptodomex {pr}`2966`, pycryptodome {pr}`2965`
diff --git a/src/core/pre.js b/src/core/pre.js
index 9a8b6e21a..9139b15c8 100644
--- a/src/core/pre.js
+++ b/src/core/pre.js
@@ -2,4 +2,5 @@ const API = Module.API;
 const Hiwire = {};
 const Tests = {};
 API.tests = Tests;
+API.version = "0.22.0.dev0";
 Module.hiwire = Hiwire;
diff --git a/src/js/api.ts b/src/js/api.ts
index 6137544a9..3a529d84e 100644
--- a/src/js/api.ts
+++ b/src/js/api.ts
@@ -7,6 +7,7 @@ import { loadPackage, loadedPackages } from "./load-package";
 import { isPyProxy, PyBuffer, PyProxy, TypedArray } from "./pyproxy.gen";
 import { PythonError } from "./error_handling.gen";
 import { loadBinaryFile } from "./compat";
+import version from "./version";
 export { loadPackage, loadedPackages, isPyProxy };
 import "./error_handling.gen.js";
 
@@ -29,16 +30,6 @@ export let pyodide_py: PyProxy; // actually defined in loadPyodide (see pyodide.
  */
 export let globals: PyProxy; // actually defined in loadPyodide (see pyodide.js)
 
-/**
- *
- * The Pyodide version.
- *
- * It can be either the exact release version (e.g. ``0.1.0``), or
- * the latest release version followed by the number of commits since, and
- * the git hash of the current commit (e.g. ``0.1.0-1-bd84646``).
- */
-export let version: string = ""; // actually defined in loadPyodide (see pyodide.js)
-
 /**
  * Just like `runPython` except uses a different globals dict and gets
  * `eval_code` from `_pyodide` so that it can work before `pyodide` is imported.
diff --git a/src/js/pyodide.ts b/src/js/pyodide.ts
index 91eef6705..6bb291a94 100644
--- a/src/js/pyodide.ts
+++ b/src/js/pyodide.ts
@@ -11,6 +11,7 @@ import {
 } from "./compat";
 
 import { createModule, setStandardStreams, setHomeDirectory } from "./module";
+import version from "./version";
 
 import type { PyodideInterface } from "./api.js";
 import type { PyProxy, PyProxyDict } from "./pyproxy.gen";
@@ -34,6 +35,8 @@ export type {
 
 export type Py2JsResult = any;
 
+export { version };
+
 /**
  * A proxy around globals that falls back to checking for a builtin if has or
  * get fails to find a global with the given key. Note that this proxy is
@@ -144,11 +147,9 @@ function finalizeBootstrap(API: any, config: ConfigType) {
   API.pyodide_code = import_module("pyodide.code");
   API.pyodide_ffi = import_module("pyodide.ffi");
   API.package_loader = import_module("pyodide._package_loader");
-  API.version = API.pyodide_py.__version__;
 
   // copy some last constants onto public API.
   pyodide.pyodide_py = API.pyodide_py;
-  pyodide.version = API.version;
   pyodide.globals = API.globals;
   return pyodide;
 }
@@ -327,6 +328,15 @@ export async function loadPyodide(
     throw Module.exited.toThrow;
   }
 
+  if (API.version !== version) {
+    throw new Error(
+      `\
+Pyodide version does not match: '${version}' <==> '${API.version}'. \
+If you updated the Pyodide version, make sure you also updated the 'indexURL' parameter passed to loadPyodide.\
+`
+    );
+  }
+
   // Disable further loading of Emscripten file_packager stuff.
   Module.locateFile = (path: string) => {
     throw new Error("Didn't expect to load any more file_packager files!");
@@ -337,6 +347,7 @@ export async function loadPyodide(
   Module._pyodide_init();
 
   const pyodide = finalizeBootstrap(API, config);
+
   // API.runPython works starting here.
   if (!pyodide.version.includes("dev")) {
     // Currently only used in Node to download packages the first time they are
@@ -344,7 +355,7 @@ export async function loadPyodide(
     API.setCdnUrl(`https://cdn.jsdelivr.net/pyodide/v${pyodide.version}/full/`);
   }
   await API.packageIndexReady;
-  if (API.repodata_info.version !== pyodide.version) {
+  if (API.repodata_info.version !== version) {
     throw new Error("Lock file version doesn't match Pyodide version");
   }
   API.package_loader.init_loaded_packages();
diff --git a/src/js/pyodide.umd.ts b/src/js/pyodide.umd.ts
index a7bfb8040..eb4963116 100644
--- a/src/js/pyodide.umd.ts
+++ b/src/js/pyodide.umd.ts
@@ -1,3 +1,3 @@
-import { loadPyodide } from "./pyodide";
-export { loadPyodide };
+import { loadPyodide, version } from "./pyodide";
+export { loadPyodide, version };
 (globalThis as any).loadPyodide = loadPyodide;
diff --git a/src/js/version.ts b/src/js/version.ts
new file mode 100644
index 000000000..fb540bcbf
--- /dev/null
+++ b/src/js/version.ts
@@ -0,0 +1,10 @@
+/**
+ *
+ * The Pyodide version.
+ *
+ * The version here follows PEP440 which is different from the one in package.json,
+ * as we want to compare this with the version of Pyodide Python package without conversion.
+ */
+const version: string = "0.22.0.dev0";
+
+export default version;
diff --git a/src/tests/test_pyodide.py b/src/tests/test_pyodide.py
index 029691218..c8b1178ea 100644
--- a/src/tests/test_pyodide.py
+++ b/src/tests/test_pyodide.py
@@ -1126,6 +1126,24 @@ def test_home_directory(selenium_standalone_noload):
     )
 
 
+def test_version_variable(selenium):
+    js_version = selenium.run_js(
+        """
+        return pyodide.version
+        """
+    )
+
+    core_version = selenium.run_js(
+        """
+        return pyodide._api.version
+        """
+    )
+
+    from pyodide import __version__ as py_version
+
+    assert js_version == py_version == core_version
+
+
 def test_sys_path0(selenium):
     selenium.run_js(
         """
diff --git a/tools/bump_version.py b/tools/bump_version.py
index fbab4253c..f51b5771e 100755
--- a/tools/bump_version.py
+++ b/tools/bump_version.py
@@ -64,6 +64,16 @@ PYTHON_TARGETS = [
         build_version_pattern(r"version\s*=\s*{{{python_version}}}"),
         prerelease=False,
     ),
+    Target(
+        ROOT / "src/js/version.ts",
+        build_version_pattern('version: string = "{python_version}"'),
+        prerelease=True,
+    ),
+    Target(
+        ROOT / "src/core/pre.js",
+        build_version_pattern('API.version = "{python_version}"'),
+        prerelease=True,
+    ),
 ]
 
 JS_TARGETS = [