diff --git a/api/src/engine/connectors/exareme/transformations.ts b/api/src/engine/connectors/exareme/transformations.ts
index f54d8caa775ed1603d1c956ab1c2614283944062..b4a12d7dd02ef4a401c2af3bf7f115aba18d1b4f 100644
--- a/api/src/engine/connectors/exareme/transformations.ts
+++ b/api/src/engine/connectors/exareme/transformations.ts
@@ -101,9 +101,7 @@ dataToHeatmap.registerFunction(
       matrix[elem.y][elem.x] = elem.value;
     });
 
-    matrix.reverse();
-
-    return matrix;
+    return matrix.reverse();
   },
   '<a<o>:a<a<n>>',
 );