diff --git a/src/components/CallRiskScoreBar.vue b/src/components/CallRiskScoreBar.vue
index 232e5e6..54e76f5 100644
--- a/src/components/CallRiskScoreBar.vue
+++ b/src/components/CallRiskScoreBar.vue
@@ -13,7 +13,7 @@ onMounted(() => {
   drawScale(id, d3.interpolateRdYlGn);
 });
 
-function drawScale(id: string, interpolator: number) {
+function drawScale(id: string, interpolator: (t: number) => string) {
   var data = Array.from(Array(100).keys());
 
   var cScale = d3.scaleSequential().interpolator(interpolator).domain([0, 99]);