diff --git a/public/app/plugins/panel/heatmap/heatmap_tooltip.ts b/public/app/plugins/panel/heatmap/heatmap_tooltip.ts
index 531ed8ca5b2..5ec0a8fa308 100644
--- a/public/app/plugins/panel/heatmap/heatmap_tooltip.ts
+++ b/public/app/plugins/panel/heatmap/heatmap_tooltip.ts
@@ -97,7 +97,7 @@ export class HeatmapTooltip {
       // legend and tooltip gets one more decimal precision
       // than graph legend ticks
       let decimals = (this.panelCtrl.decimals || -1) + 1;
-      valueFormatter = this.valueFormatter(this.panel.tooltipDecimals, this.panelCtrl.scaledDecimals + 2);
+      valueFormatter = this.valueFormatter(decimals, this.panelCtrl.scaledDecimals + 2);
     }
 
     let tooltipHtml = `<div class="graph-tooltip-time">${time}</div>