diff --git a/src/util/qpolygon-utils.js b/src/util/qpolygon-utils.js
index 15b9e569..33737856 100644
--- a/src/util/qpolygon-utils.js
+++ b/src/util/qpolygon-utils.js
@@ -7579,7 +7579,12 @@ export const drawRidgeRoof = (roofId, canvas, textMode) => {
 
               hipBasePoint = { x1: line.x1, y1: line.y1, x2: line.x2, y2: line.y2 }
               point = [mergePoint[0].x, mergePoint[0].y, mergePoint[3].x, mergePoint[3].y]
-              const theta = Big(Math.acos(Big(line.line.attributes.planeSize).div(line.line.attributes.actualSize)))
+              const theta = Big(Math.acos(Big(line.line.attributes.planeSize).div(
+                line.line.attributes.actualSize === 0 ||
+                line.line.attributes.actualSize === '' ||
+                line.line.attributes.actualSize === undefined ?
+                line.line.attributes.planeSize : line.line.attributes.actualSize
+              )))
                 .times(180)
                 .div(Math.PI)
                 .round(1)
@@ -9223,7 +9228,11 @@ const getSortedPoint = (points, lines) => {
 const reCalculateSize = (line) => {
   const oldPlaneSize = line.attributes.planeSize
   const oldActualSize = line.attributes.actualSize
-  const theta = Big(Math.acos(Big(oldPlaneSize).div(oldActualSize)))
+  const theta = Big(Math.acos(Big(oldPlaneSize).div(
+    oldActualSize === 0 || oldActualSize === '' || oldActualSize === undefined ?
+      oldPlaneSize :
+      oldActualSize
+  )))
     .times(180)
     .div(Math.PI)
   const planeSize = calcLinePlaneSize({