diff --git a/public/app/plugins/datasource/prometheus/result_transformer.ts b/public/app/plugins/datasource/prometheus/result_transformer.ts
index b33a2b0322f..1cc3003b48a 100644
--- a/public/app/plugins/datasource/prometheus/result_transformer.ts
+++ b/public/app/plugins/datasource/prometheus/result_transformer.ts
@@ -604,7 +604,7 @@ export function getOriginalMetricName(labelData: { [key: string]: string }) {
 }
 
 function mergeHeatmapFrames(frames: DataFrame[]): DataFrame[] {
-  if (frames.length === 0) {
+  if (frames.length === 0 || (frames.length === 1 && frames[0].length === 0)) {
     return [];
   }