diff --git a/types/chart.js/chart.js-tests.ts b/types/chart.js/chart.js-tests.ts
index e60486cee0..a055dcac09 100644
--- a/types/chart.js/chart.js-tests.ts
+++ b/types/chart.js/chart.js-tests.ts
@@ -279,3 +279,17 @@ const linearScaleChart: Chart = new Chart(ctx, {
         }
     }
 });
+
+// custom tooltips
+const customTooltipsPieChart = new Chart(ctx, {
+    type: 'pie',
+    data: {},
+    options: {
+        tooltips: {
+            enabled: false,
+            custom: (tooltipModel) => {
+                // do whatever
+            },
+        },
+    },
+});
diff --git a/types/chart.js/index.d.ts b/types/chart.js/index.d.ts
index 3c49e97e13..fbc29a95c7 100644
--- a/types/chart.js/index.d.ts
+++ b/types/chart.js/index.d.ts
@@ -302,7 +302,7 @@ declare namespace Chart {
 
     interface ChartTooltipOptions {
         enabled?: boolean;
-        custom?(a: any): void;
+        custom?: (tooltipModel: ChartTooltipModel) => void;
         mode?: InteractionMode;
         intersect?: boolean;
         backgroundColor?: ChartColor;
@@ -341,6 +341,47 @@ declare namespace Chart {
         borderWidth?: number;
     }
 
+    interface ChartTooltipModel {
+        backgroundColor: string;
+        bodyFontColor: string;
+        bodyFontSize: number;
+        bodySpacing: number;
+        borderColor: string;
+        borderWidth: number;
+        caretSize: number;
+        caretX: number;
+        caretY: number;
+        cornerRadius: number;
+        displayColors: boolean;
+        footerFontColor: string;
+        footerFontSize: number;
+        footerMarginTop: number;
+        footerSpacing: number;
+        height: number;
+        legendColorBackground: string;
+        opacity: number;
+        titleFontColor: string;
+        titleFontSize: number;
+        titleMarginBottom: number;
+        titleSpacing: number;
+        width: number;
+        x: number;
+        xAlign: string;
+        xPadding: number;
+        y: number;
+        yAlign: string;
+        yPadding: number;
+        _bodyAlign: string;
+        _bodyFontFamily: string;
+        _bodyFontStyle: string;
+        _footerAlign: string;
+        _footerFontFamily: string;
+        _footerFontStyle: string;
+        _titleAlign: string;
+        _titleFontFamily: string;
+        _titleFontStyle: string;
+    }
+
     // NOTE: declare plugin options as interface instead of inline '{ [plugin: string]: any }'
     // to allow module augmentation in case some plugins want to strictly type their options.
     interface ChartPluginsOptions {