diff --git a/src/util/qpolygon-utils.js b/src/util/qpolygon-utils.js
index b9e812f3..e29db805 100644
--- a/src/util/qpolygon-utils.js
+++ b/src/util/qpolygon-utils.js
@@ -572,8 +572,14 @@ export const drawGableRoof = (roofId, canvas, textMode) => {
     }
 
     const findEdge = { vertex1: { x: midX, y: midY }, vertex2: { x: midX + roofVector.x * offset, y: midY + roofVector.y * offset } }
-    const edgeDx = Big(findEdge.vertex2.x).minus(Big(findEdge.vertex1.x)).toNumber()
-    const edgeDy = Big(findEdge.vertex2.y).minus(Big(findEdge.vertex1.y)).toNumber()
+    const edgeDx =
+      Big(findEdge.vertex2.x).minus(Big(findEdge.vertex1.x)).abs().toNumber() < 0.1
+        ? 0
+        : Big(findEdge.vertex2.x).minus(Big(findEdge.vertex1.x)).toNumber()
+    const edgeDy =
+      Big(findEdge.vertex2.y).minus(Big(findEdge.vertex1.y)).abs().toNumber() < 0.1
+        ? 0
+        : Big(findEdge.vertex2.y).minus(Big(findEdge.vertex1.y)).toNumber()
     const edgeLength = Math.sqrt(edgeDx * edgeDx + edgeDy * edgeDy)
     const edgeVector = { x: edgeDx / edgeLength, y: edgeDy / edgeLength }
 
@@ -582,8 +588,10 @@ export const drawGableRoof = (roofId, canvas, textMode) => {
       const lineEdge = { vertex1: { x: roofLine.x1, y: roofLine.y1 }, vertex2: { x: roofLine.x2, y: roofLine.y2 } }
       const intersect = edgesIntersection(lineEdge, findEdge)
       if (intersect) {
-        const intersectDx = Big(intersect.x).minus(Big(findEdge.vertex1.x)).toNumber()
-        const intersectDy = Big(intersect.y).minus(Big(findEdge.vertex1.y)).toNumber()
+        const intersectDx =
+          Big(intersect.x).minus(Big(findEdge.vertex1.x)).abs().toNumber() < 0.1 ? 0 : Big(intersect.x).minus(Big(findEdge.vertex1.x)).toNumber()
+        const intersectDy =
+          Big(intersect.y).minus(Big(findEdge.vertex1.y)).abs().toNumber() < 0.1 ? 0 : Big(intersect.y).minus(Big(findEdge.vertex1.y)).toNumber()
         const intersectLength = Math.sqrt(intersectDx * intersectDx + intersectDy * intersectDy)
         const intersectVector = { x: intersectDx / intersectLength, y: intersectDy / intersectLength }
         if (edgeVector.x === intersectVector.x && edgeVector.y === intersectVector.y) {