diff --git a/readme.md b/readme.md
index d73391c..8440b93 100644
--- a/readme.md
+++ b/readme.md
@@ -1,6 +1,6 @@
 [![Tests](https://github.com/Daveiano/weewx-wdc/actions/workflows/test.yml/badge.svg)](https://github.com/Daveiano/weewx-wdc/actions/workflows/test.yml)
 ![GitHub release (latest SemVer)](https://img.shields.io/github/v/release/Daveiano/weewx-wdc?label=latest%20release&sort=semver)
-![GitHub milestone](https://img.shields.io/github/milestones/issues-open/Daveiano/weewx-wdc/18)
+![GitHub milestone](https://img.shields.io/github/milestones/issues-open/Daveiano/weewx-wdc/19)
 ![GitHub commits since latest release (by SemVer)](https://img.shields.io/github/commits-since/Daveiano/weewx-wdc/latest)
 ![GitHub all releases](https://img.shields.io/github/downloads/Daveiano/weewx-wdc/total)
 ![GitHub closed pull requests](https://img.shields.io/github/issues-pr-closed-raw/Daveiano/weewx-wdc)
diff --git a/skins/weewx-wdc/src/js/diagrams/d3/line.tsx b/skins/weewx-wdc/src/js/diagrams/d3/line.tsx
index 77a1a37..5fe5da0 100644
--- a/skins/weewx-wdc/src/js/diagrams/d3/line.tsx
+++ b/skins/weewx-wdc/src/js/diagrams/d3/line.tsx
@@ -436,7 +436,7 @@ export const D3LineDiagram: FunctionComponent<LineDiagramBaseProps> = (
         svgElement
           .append("g")
           .selectAll("dot")
-          .data(dataSet.data.filter((d: any) => d.y !== null))
+          .data(dataSet.data)
           .enter()
           .append("circle")
           .attr("cx", (d: any) => {
@@ -456,7 +456,7 @@ export const D3LineDiagram: FunctionComponent<LineDiagramBaseProps> = (
       if (observationProps.enableArea) {
         svgElement
           .append("path")
-          .datum(dataSet.data.filter((d: any) => d.y !== null) as any)
+          .datum(dataSet.data as any)
           .attr("fill", colors[index])
           .attr(
             "fill-opacity",
@@ -490,10 +490,7 @@ export const D3LineDiagram: FunctionComponent<LineDiagramBaseProps> = (
           "stroke-width",
           observationProps.lineWidth ? observationProps.lineWidth : 2
         )
-        .attr(
-          "d",
-          lineGenerator(dataSet.data.filter((d: any) => d.y !== null) as any)
-        );
+        .attr("d", lineGenerator(dataSet.data as any));
     });
 
     // Markers.
diff --git a/skins/weewx-wdc/src/js/index.tsx b/skins/weewx-wdc/src/js/index.tsx
index 28f005e..f951198 100644
--- a/skins/weewx-wdc/src/js/index.tsx
+++ b/skins/weewx-wdc/src/js/index.tsx
@@ -128,6 +128,8 @@ diagrams.forEach((diagram) => {
         diagram.dataset.value.replace(/'/g, '"')
       );
 
+      // Filter out null values.
+      // @see https://groups.google.com/g/weewx-development/c/frA0Vc9Ku9Q
       series.forEach((serie, index) => {
         data = [
           ...data,