diff --git a/src/core/init.js b/src/core/init.js
index 764437b1ff..78f93656e9 100644
--- a/src/core/init.js
+++ b/src/core/init.js
@@ -16,7 +16,7 @@ export const _globalInit = () => {
   // Could have been any property defined within the p5 constructor.
   // If that property is already a part of the global object,
   // this code has already run before, likely due to a duplicate import
-  if (typeof window._setupDone !== 'undefined') {
+  if (typeof window.p5 !== 'undefined') {
     console.warn(
       'p5.js seems to have been imported multiple times. Please remove the duplicate import'
     );
diff --git a/src/core/main.js b/src/core/main.js
index a5c9a6c93d..8d571b06e5 100644
--- a/src/core/main.js
+++ b/src/core/main.js
@@ -125,11 +125,17 @@ class p5 {
     // If the user has created a global setup or draw function,
     // assume "global" mode and make everything global (i.e. on the window)
     if (!sketch) {
+      if (typeof window.p5 !== 'undefined') {
+        console.warn('p5.js appears to have been imported multiple times. This could cause errors.');
+        return;
+      }
       this._isGlobal = true;
+      window._p5Instance = this;
       if (window.hitCriticalError) {
         return;
       }
       p5.instance = this;
+      window.p5 = p5;
 
       // Loop through methods on the prototype and attach them to the window
       // All methods and properties with name starting with '_' will be skipped