diff --git a/package-lock.json b/package-lock.json
index da58db37..401ed78e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "react-modal",
-  "version": "3.15.1",
+  "version": "3.14.4",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
@@ -1564,7 +1564,7 @@
     "array-from": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/array-from/-/array-from-2.1.1.tgz",
-      "integrity": "sha512-GQTc6Uupx1FCavi5mPzBvVT7nEOeWMmUA9P95wpfpW1XwMSKs+KaymD5C2Up7KAUKg/mYwbsUYzdZWcoajlNZg==",
+      "integrity": "sha1-z+nYwmYoudxa7MYqn12PHzUsEZU=",
       "dev": true
     },
     "array-includes": {
diff --git a/src/components/ModalPortal.js b/src/components/ModalPortal.js
index 867f756f..4db77201 100644
--- a/src/components/ModalPortal.js
+++ b/src/components/ModalPortal.js
@@ -17,6 +17,18 @@ const CLASS_NAMES = {
   content: "ReactModal__Content"
 };
 
+/**
+ * We need to support the deprecated `KeyboardEvent.keyCode` in addition to
+ * `KeyboardEvent.code` for apps that still support IE11. Can be removed when
+ * `react-modal` only supports React >18 (which dropped IE support).
+ */
+const isTabKey = event => {
+  event.code === "Tab" || event.keyCode === 9;
+};
+const isEscKey = event => {
+  event.code === "Escape" || event.keyCode === 27;
+};
+
 let ariaHiddenInstances = 0;
 
 export default class ModalPortal extends Component {
@@ -281,11 +293,11 @@ export default class ModalPortal extends Component {
   };
 
   handleKeyDown = event => {
-    if (event.code === "Tab") {
+    if (isTabKey(event)) {
       scopeTab(this.content, event);
     }
 
-    if (this.props.shouldCloseOnEsc && event.code === "Escape") {
+    if (this.props.shouldCloseOnEsc && isEscKey(event)) {
       event.stopPropagation();
       this.requestClose(event);
     }