diff --git a/src/core/main.js b/src/core/main.js
index 0e19d75ec1..1e54342d81 100644
--- a/src/core/main.js
+++ b/src/core/main.js
@@ -331,9 +331,8 @@ class p5 {
     const methods = Object.getOwnPropertyNames(p5.prototype._registeredMethods);
 
     for (const prop of methods) {
-      this._registeredMethods[prop] = p5.prototype._registeredMethods[
-        prop
-      ].slice();
+      this._registeredMethods[prop] =
+        p5.prototype._registeredMethods[prop].slice();
     }
 
     if (window.DeviceOrientationEvent) {
@@ -406,7 +405,7 @@ class p5 {
       }
     };
 
-    this._runIfPreloadsAreDone = function() {
+    this._runIfPreloadsAreDone = function () {
       const context = this._isGlobal ? window : this;
       if (context._preloadCount === 0) {
         const loadingScreen = document.getElementById(context._loadingScreenId);
@@ -425,7 +424,7 @@ class p5 {
       }
     };
 
-    this._decrementPreload = function() {
+    this._decrementPreload = function () {
       const context = this._isGlobal ? window : this;
       if (!context._preloadDone && typeof context.preload === 'function') {
         context._setProperty('_preloadCount', context._preloadCount - 1);
@@ -433,7 +432,7 @@ class p5 {
       }
     };
 
-    this._wrapPreload = function(obj, fnName) {
+    this._wrapPreload = function (obj, fnName) {
       return (...args) => {
         //increment counter
         this._incrementPreload();
@@ -442,7 +441,7 @@ class p5 {
       };
     };
 
-    this._incrementPreload = function() {
+    this._incrementPreload = function () {
       const context = this._isGlobal ? window : this;
       // Do nothing if we tried to increment preloads outside of `preload`
       if (context._preloadDone) return;
@@ -524,8 +523,10 @@ class p5 {
         this._setProperty('deltaTime', this.deltaTime);
         this._frameRate = 1000.0 / this.deltaTime;
         this.redraw();
-        this._lastTargetFrameTime = Math.max(this._lastTargetFrameTime
-          + target_time_between_frames, now);
+        this._lastTargetFrameTime = Math.max(
+          this._lastTargetFrameTime + target_time_between_frames,
+          now
+        );
         this._lastRealFrameTime = now;
 
         // If the user is actually using mouse module, then update
@@ -550,6 +551,27 @@ class p5 {
     };
 
     this._setProperty = (prop, value) => {
+      // Intercept keyCode writes to show Friendly Error warning
+      if (prop === 'keyCode') {
+        if (!this._keyCodeWarningShown) {
+          p5._friendlyError(
+            'keyCode === is deprecated in p5.js 2.0. Please use keyIsDown() instead.\n' +
+              'See https://beta.p5js.org/reference/p5/keyisdown/ for more information.'
+          );
+          this._keyCodeWarningShown = true;
+        }
+
+        this.keyCode = value;
+        this._keyCode = value;
+
+        if (this._isGlobal) {
+          window.keyCode = value;
+          window._keyCode = value;
+        }
+        return;
+      }
+
+      // Default behavior for all other props
       this[prop] = value;
       if (this._isGlobal) {
         window[prop] = value;
@@ -596,7 +618,7 @@ class p5 {
      */
     this.remove = () => {
       // Remove start listener to prevent orphan canvas being created
-      if(this._startListener){
+      if (this._startListener) {
         window.removeEventListener('load', this._startListener, false);
       }
       const loadingScreen = document.getElementById(this._loadingScreenId);
diff --git a/test/manual-test-examples/events/keyCode-warning-sketch.js b/test/manual-test-examples/events/keyCode-warning-sketch.js
new file mode 100644
index 0000000000..4125b8e1aa
--- /dev/null
+++ b/test/manual-test-examples/events/keyCode-warning-sketch.js
@@ -0,0 +1,21 @@
+function setup() {
+  createCanvas(windowWidth, windowHeight);
+  background(0);
+  fill(255);
+  textSize(20);
+  text('Press any arrow key and check console for warning', 40, height / 2);
+}
+
+function draw() {
+  if (typeof keyCode === 'undefined') return; // avoid error before first key press
+
+  if (keyCode === LEFT_ARROW) {
+    background(255, 0, 0);
+  } else if (keyCode === RIGHT_ARROW) {
+    background(0, 255, 0);
+  } else if (keyCode === UP_ARROW) {
+    background(0, 0, 255);
+  } else if (keyCode === DOWN_ARROW) {
+    background(255, 255, 0);
+  }
+}
diff --git a/test/manual-test-examples/events/keyCode-warning.html b/test/manual-test-examples/events/keyCode-warning.html
new file mode 100644
index 0000000000..154c5b9aa9
--- /dev/null
+++ b/test/manual-test-examples/events/keyCode-warning.html
@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<html>
+
+<head>
+  <meta charset="utf-8">
+  <meta http-equiv="X-UA-Compatible" content="IE=edge">
+  <title></title>
+  <link rel="stylesheet" href="../styles.css">
+
+  <script language="javascript" src="../../../lib/p5.js"></script>
+  <!-- uncomment lines below to include extra p5 libraries -->
+  <!--<script language="javascript" src="../addons/p5.sound.js"></script>-->
+  <script language="javascript" type="text/javascript" src="keyCode-warning-sketch.js"></script>
+  <!-- webgl stats: <script src="../stats.js"></script> -->
+</head>
+
+<body>
+  <header>
+    <p>Deprecated keyCode warning test</p>
+  </header>
+</body>
+
+</html>
\ No newline at end of file