diff --git a/tools/rw-heatmaps/pkg/chart/heatmap.go b/tools/rw-heatmaps/pkg/chart/heatmap.go
index eef8e04ac161..f61cff0e097d 100644
--- a/tools/rw-heatmaps/pkg/chart/heatmap.go
+++ b/tools/rw-heatmaps/pkg/chart/heatmap.go
@@ -71,7 +71,7 @@ func plotIndividualHeatMap(title, plotType string, records []dataset.DataRecord)
 	// Populate X and Y axis data from records
 	xCoords, yCoords := populateGridAxes(records)
 
-	gridData := &HeatMapGrid{
+	gridData := &heatMapGrid{
 		x: xCoords,
 		y: yCoords,
 		z: make([][]float64, len(yCoords)),
diff --git a/tools/rw-heatmaps/pkg/chart/heatmap_grid.go b/tools/rw-heatmaps/pkg/chart/heatmap_grid.go
index 5355264e9f1f..165a5d522ad6 100644
--- a/tools/rw-heatmaps/pkg/chart/heatmap_grid.go
+++ b/tools/rw-heatmaps/pkg/chart/heatmap_grid.go
@@ -14,27 +14,27 @@
 
 package chart
 
-// HeatMapGrid holds X, Y, Z values for a heatmap.
-type HeatMapGrid struct {
+// heatMapGrid holds X, Y, Z values for a heatmap.
+type heatMapGrid struct {
 	x, y []float64
 	z    [][]float64 // The Z values should be arranged in a 2D slice.
 }
 
 // Dims returns the number of elements in the grid.
 // It implements the plotter.GridXYZ interface.
-func (h *HeatMapGrid) Dims() (int, int) {
+func (h *heatMapGrid) Dims() (int, int) {
 	return len(h.x), len(h.y)
 }
 
 // Z returns the value of a grid cell at (c, r).
 // It implements the plotter.GridXYZ interface.
-func (h *HeatMapGrid) Z(c, r int) float64 {
+func (h *heatMapGrid) Z(c, r int) float64 {
 	return h.z[r][c]
 }
 
 // X returns the coordinate for the column at index c.
 // It implements the plotter.GridXYZ interface.
-func (h *HeatMapGrid) X(c int) float64 {
+func (h *heatMapGrid) X(c int) float64 {
 	if c >= len(h.x) {
 		panic("index out of range")
 	}
@@ -43,7 +43,7 @@ func (h *HeatMapGrid) X(c int) float64 {
 
 // Y returns the coordinate for the row at index r.
 // It implements the plotter.GridXYZ interface.
-func (h *HeatMapGrid) Y(r int) float64 {
+func (h *heatMapGrid) Y(r int) float64 {
 	if r >= len(h.y) {
 		panic("index out of range")
 	}