diff --git a/packages/mermaid/src/rendering-util/createGradient.spec.ts b/packages/mermaid/src/rendering-util/createGradient.spec.ts
index deb5ed051b..aa92c40e2c 100644
--- a/packages/mermaid/src/rendering-util/createGradient.spec.ts
+++ b/packages/mermaid/src/rendering-util/createGradient.spec.ts
@@ -236,7 +236,7 @@ const calculatePolygonBBox = (points: number[][]) => {
 const calculatePathBBox = (path: SVGPathElement, nsteps = 100) => {
   const length = path.getTotalLength();
   const step = length / nsteps;
-  const points = [];
+  const points: number[][] = [];
   for (let i = 0; i <= length; i += step) {
     const point = path.getPointAtLength(i);
     points.push([point.x, point.y]);