diff --git a/HISTORY.md b/HISTORY.md
index 52ec70ba8f..f29f620bf4 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -4,6 +4,7 @@
 
 2024-01-15
 * new dev version for v9.2.1
+* threads: fixed a raycasting glitch, thanks, Dariusz, for yet another brilliant catch!
 
 ## 9.2.0:
 * **New Features:**
diff --git a/snap.html b/snap.html
index 3f8565afe7..31edcfaad2 100755
--- a/snap.html
+++ b/snap.html
@@ -17,7 +17,7 @@
         <script src="src/symbols.js?version=2023-07-13"></script>
         <script src="src/widgets.js?version=2023-05-24"></script>
         <script src="src/blocks.js?version=2023-11-24"></script>
-        <script src="src/threads.js?version=2024-01-10"></script>
+        <script src="src/threads.js?version=2024-01-15"></script>
         <script src="src/objects.js?version=2024-01-10"></script>
         <script src="src/scenes.js?version=2022-10-29"></script>
         <script src="src/gui.js?version=2024-01-15"></script>
diff --git a/src/threads.js b/src/threads.js
index 9a15459bf3..d3fc5e4b60 100644
--- a/src/threads.js
+++ b/src/threads.js
@@ -65,7 +65,7 @@ StagePickerMorph, CustomBlockDefinition, CommentMorph*/
 
 /*jshint esversion: 11, bitwise: false, evil: true*/
 
-modules.threads = '2024-January-10';
+modules.threads = '2024-January-15';
 
 var ThreadManager;
 var Process;
@@ -6118,7 +6118,7 @@ Process.prototype.reportRayLengthTo = function (name, relativeAngle = 0) {
     top = targetBounds.top();
     bottom = targetBounds.bottom();
     left = targetBounds.left();
-    right = targetBounds.right();
+    right = targetBounds.right() - 1;
 
     // test if already inside the target
     if (targetBounds.containsPoint(rc)) {