diff --git a/tensorboard/components/vz_line_chart/vz-line-chart.ts b/tensorboard/components/vz_line_chart/vz-line-chart.ts
index 7e95ba9ddb..a3ad96e930 100644
--- a/tensorboard/components/vz_line_chart/vz-line-chart.ts
+++ b/tensorboard/components/vz_line_chart/vz-line-chart.ts
@@ -355,7 +355,7 @@ Polymer({
       _attached) {
     // Find the actual xComponentsCreationMethod.
     if (!xType && !xComponentsCreationMethod) {
-      xComponentsCreationMethod = () => vz_line_chart.stepX;
+      xComponentsCreationMethod = vz_line_chart.stepX;
     } else if (xType) {
       xComponentsCreationMethod = () =>
           vz_line_chart.getXComponents(xType);