diff --git a/subjects/mouse-trap/README.md b/subjects/mouse-trap/README.md
index 1ad7ec865..2d531980b 100644
--- a/subjects/mouse-trap/README.md
+++ b/subjects/mouse-trap/README.md
@@ -10,7 +10,7 @@ Develop a trap to capture the elements when the mouse is getting too close to th
 
 - Create a function `setBox` which sets a box with the class `box` in the center of the page ; when a circle is inside that box, it has to be purple (use the CSS global variable `var(--purple)` as `background`) ; once a circle enters the box, it is trapped inside and cannot go out of it anymore.
 
-> Hint: do not use operators like `<=` or `=>`, a circle has to be trapped **strictly** inside the box
+> Hint: Be careful, a circle cannot overlap the box which has walls of `1px`, it has to be trapped **strictly** inside.
 
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