diff --git a/packages/element/src/linearElementEditor.ts b/packages/element/src/linearElementEditor.ts
index 80541b2ce..2acb77a2a 100644
--- a/packages/element/src/linearElementEditor.ts
+++ b/packages/element/src/linearElementEditor.ts
@@ -298,9 +298,9 @@ export class LinearElementEditor {
           element.points[selectedIndex === 0 ? 1 : selectedIndex - 1];
         customLineAngle =
           linearElementEditor.customLineAngle ??
-          Math.atan(
-            (element.points[selectedIndex][1] - referencePoint[1]) /
-              (element.points[selectedIndex][0] - referencePoint[0]),
+          Math.atan2(
+            element.points[selectedIndex][1] - referencePoint[1],
+            element.points[selectedIndex][0] - referencePoint[0],
           );
 
         const [width, height] = LinearElementEditor._getShiftLockedDelta(
diff --git a/packages/element/src/sizeHelpers.ts b/packages/element/src/sizeHelpers.ts
index 0bb7d0456..a1d7f6811 100644
--- a/packages/element/src/sizeHelpers.ts
+++ b/packages/element/src/sizeHelpers.ts
@@ -145,7 +145,7 @@ export const getLockedLinearCursorAlignSize = (
   let width = x - originX;
   let height = y - originY;
 
-  const angle = Math.atan(height / width) as Radians;
+  const angle = Math.atan2(height, width) as Radians;
   let lockedAngle = (Math.round(angle / SHIFT_LOCKING_ANGLE) *
     SHIFT_LOCKING_ANGLE) as Radians;