diff --git a/src/gamelib.js b/src/gamelib.js
index ae76391..3af2d31 100644
--- a/src/gamelib.js
+++ b/src/gamelib.js
@@ -52,13 +52,19 @@ export class Gamelib {
         });
 
         canvasElement.addEventListener("mousedown", (ev) => {
+            const ratioX = canvasElement.width / canvasElement.clientWidth;
+            const ratioY = canvasElement.height / canvasElement.clientHeight;
+
             this.mouseButtonsPressed.add(ev.button);
-            this.mouseDownHandlers.get(ev.button)?.(ev.offsetX, ev.offsetY);
+            this.mouseDownHandlers.get(ev.button)?.(ev.offsetX * ratioX, ev.offsetY * ratioY);
         });
 
         canvasElement.addEventListener("mouseup", (ev) => {
+            const ratioX = canvasElement.width / canvasElement.clientWidth;
+            const ratioY = canvasElement.height / canvasElement.clientHeight;
+
             this.mouseButtonsPressed.delete(ev.button);
-            this.mouseUpHandlers.get(ev.button)?.(ev.offsetX, ev.offsetY);
+            this.mouseUpHandlers.get(ev.button)?.(ev.offsetX * ratioX, ev.offsetY * ratioY);
         });
 
         canvasElement.addEventListener("contextmenu", (ev) => {