diff --git a/components/mjs/startup/hasown.js b/components/mjs/startup/hasown.js
new file mode 100644
index 000000000..b886b536b
--- /dev/null
+++ b/components/mjs/startup/hasown.js
@@ -0,0 +1,10 @@
+import {MathJax} from '#js/components/global.js';
+
+if (!Object.hasOwn && MathJax.config.startup.polyfillHasOwn) {
+  Object.hasOwn = function (el, prop) {
+    if (typeof el === 'undefined' || el === null) {
+      throw new TypeError('Cannot convert undefined or null to object');
+    }
+    return Object.prototype.hasOwnProperty.call(Object(el), prop);
+  }
+}
diff --git a/components/mjs/startup/init.js b/components/mjs/startup/init.js
index f34d29799..8ae46803d 100644
--- a/components/mjs/startup/init.js
+++ b/components/mjs/startup/init.js
@@ -1,3 +1,4 @@
+import './hasown.js';
 import './lib/startup.js';
 
 import {combineDefaults} from '#js/components/global.js';
diff --git a/ts/components/startup.ts b/ts/components/startup.ts
index 777bd5c70..49cf0e3bf 100644
--- a/ts/components/startup.ts
+++ b/ts/components/startup.ts
@@ -620,6 +620,7 @@ if (typeof MathJax._.startup === 'undefined') {
     typeset: true,
     ready: Startup.defaultReady.bind(Startup),
     pageReady: Startup.defaultPageReady.bind(Startup),
+    polyfillHasOwn: true,
   });
   combineWithMathJax({
     startup: Startup,