diff --git a/src/extension/figure/line.ts b/src/extension/figure/line.ts
index b3c37e5a..c77b2f28 100644
--- a/src/extension/figure/line.ts
+++ b/src/extension/figure/line.ts
@@ -22,7 +22,7 @@ function getDistance (coordinate1: Coordinate, coordinate2: Coordinate): number
   return Math.sqrt(Math.pow(coordinate1.x + coordinate2.x, 2) + Math.pow(coordinate1.y + coordinate2.y, 2))
 }
 
-function getSmoothControlCoordinate (coordinates: Coordinate[]): Coordinate[] {
+function getSmoothControlCoordinate (coordinates: [Coordinate, Coordinate, Coordinate]): Coordinate[] {
   const d01 = getDistance(coordinates[0], coordinates[1])
   const d12 = getDistance(coordinates[1], coordinates[2])
   const d02 = d01 + d12
@@ -110,7 +110,7 @@ export function drawLine (ctx: CanvasRenderingContext2D, attrs: LineAttrs, style
     ctx.beginPath()
     ctx.moveTo(coordinates[0].x, coordinates[0].y)
 
-    if (smooth ?? false) {
+    if ((smooth ?? false) && length > 2) {
       let controlCoordinates: Coordinate[] = []
       for (let i = 1; i < length - 1; i++) {
         controlCoordinates = controlCoordinates.concat(getSmoothControlCoordinate([coordinates[i - 1], coordinates[i], coordinates[i + 1]]))