diff --git a/www/js/interface.js b/www/js/interface.js
index 9840a61..8d9c72e 100644
--- a/www/js/interface.js
+++ b/www/js/interface.js
@@ -147,7 +147,7 @@ const INTERFACE = {
                 let basis_y = INTERFACE_DATA.Render.offset.y + (14 * apothem);
 
                 let x = (mouse_x - basis_x) / grid_offset_x;
-                let y = -(event.offsetY - basis_y) / apothem;
+                let y = -(mouse_y - basis_y) / apothem;
             
                 let kx = Math.floor(x);
                 let ky = Math.floor(y);
@@ -178,7 +178,7 @@ const INTERFACE = {
                 let basis_y = INTERFACE_DATA.Render.offset.y + (3 * apothem);
 
                 let x = (mouse_x - basis_x) / grid_offset_x;
-                let y = (event.offsetY - basis_y) / apothem;
+                let y = (mouse_y - basis_y) / apothem;
             
                 let kx = Math.floor(x);
                 let ky = Math.floor(y);