diff --git a/sqlpage/apexcharts.js b/sqlpage/apexcharts.js
index b822f9e1..8fad6e29 100644
--- a/sqlpage/apexcharts.js
+++ b/sqlpage/apexcharts.js
@@ -53,7 +53,7 @@ sqlpage_chart = (() => {
   /** @typedef {number|string|Date} XValue */
   /** @typedef { {x:XValue, y:number|null, z?:number, fillColor?:string} } ChartPoint */
   /** @typedef { {name:string, data:ChartPoint[]} } ChartSeries */
-  /** @typedef { { [name:string]: ChartSeries } } Series */
+  /** @typedef { Map<string, ChartSeries> } Series */
 
   /** @param {XValue} x @returns {number|string} equal x values share a key */
   const x_key = (x) => (x instanceof Date ? x.getTime() : x);
@@ -199,9 +199,11 @@ sqlpage_chart = (() => {
     const points = data.points.filter(Array.isArray);
     const reference_rows = data.points.filter((row) => !Array.isArray(row));
     /** @type { Series } */
-    const series_map = {};
+    const series_map = new Map();
     for (const [name, old_x, old_y, color, z] of points) {
-      series_map[name] = series_map[name] || { name, data: [] };
+      /** @type {ChartSeries} */
+      const point_series = series_map.get(name) ?? { name, data: [] };
+      series_map.set(name, point_series);
       let x = old_x;
       let y = old_y;
       if (is_timeseries) {
@@ -210,7 +212,7 @@ sqlpage_chart = (() => {
           y = y.map((y) => new Date(y).getTime());
         else x = new Date(x);
       }
-      series_map[name].data.push({ x, y, z, fillColor: named_color(color) });
+      point_series.data.push({ x, y, z, fillColor: named_color(color) });
     }
     if (data.xmin == null) data.xmin = undefined;
     if (data.xmax == null) data.xmax = undefined;
@@ -224,7 +226,7 @@ sqlpage_chart = (() => {
     ];
     let colors = palette;
 
-    let series = Object.values(series_map);
+    let series = [...series_map.values()];
     const xaxis_type = xaxis_type_for(
       series,
       chart_type,
diff --git a/tests/end-to-end/fixtures/chart/builtin-series-names.sql b/tests/end-to-end/fixtures/chart/builtin-series-names.sql
new file mode 100644
index 00000000..c03347f7
--- /dev/null
+++ b/tests/end-to-end/fixtures/chart/builtin-series-names.sql
@@ -0,0 +1,2 @@
+SELECT 'chart' AS component, 'test-chart' AS id, 'Chart test fixture' AS title, 'bar' AS type, 4 AS marker;
+WITH points(series, x, y) AS (VALUES ('toString', 'Q1', 1), ('constructor', 'Q1', 2)) SELECT * FROM points;
diff --git a/tests/end-to-end/fixtures/chart/numeric-series-names.sql b/tests/end-to-end/fixtures/chart/numeric-series-names.sql
new file mode 100644
index 00000000..cd56fd8e
--- /dev/null
+++ b/tests/end-to-end/fixtures/chart/numeric-series-names.sql
@@ -0,0 +1,2 @@
+SELECT 'chart' AS component, 'test-chart' AS id, 'Chart test fixture' AS title, 'bar' AS type, 4 AS marker;
+WITH points(series, x, y) AS (VALUES (2024, 'Q1', 1), (2023, 'Q1', 2), ('total', 'Q1', 3)) SELECT * FROM points;
diff --git a/tests/end-to-end/fixtures/chart/test.ts b/tests/end-to-end/fixtures/chart/test.ts
index d20553a9..b2cdcba2 100644
--- a/tests/end-to-end/fixtures/chart/test.ts
+++ b/tests/end-to-end/fixtures/chart/test.ts
@@ -9,7 +9,7 @@ declare global {
         config: {
           chart: { type: string; stacked: boolean };
           xaxis: { type?: string; tickAmount?: number };
-          series: { name: string; data?: ChartPoint[] }[];
+          series: { name: string | number; data?: ChartPoint[] }[];
         };
         globals: { labels: (string | number)[] };
       };
@@ -487,6 +487,25 @@ test("keeps the color of the series when a row names a color SQLPage does not kn
   expect(fills(unknown)).toEqual(fills(plain));
 });
 
+test("renders series named after built-in JavaScript properties", async ({
+  page,
+}) => {
+  const chart = await renderChart(page, "builtin-series-names");
+
+  expect(chart.failures).toEqual([]);
+  expect(chart.series.map((s) => s.name)).toEqual(["toString", "constructor"]);
+  expect(chart.shapes).toHaveLength(2);
+});
+
+test("keeps numeric series names in the order their rows came back in", async ({
+  page,
+}) => {
+  const chart = await renderChart(page, "numeric-series-names");
+
+  expect(chart.failures).toEqual([]);
+  expect(chart.series.map((s) => s.name)).toEqual([2024, 2023, "total"]);
+});
+
 test("keeps coloring reference lines from their own row", async ({ page }) => {
   const chart = await renderChart(page, "colored-reference-line");