diff --git a/.gitignore b/.gitignore
index 97e9bcb..d984289 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,5 @@
 # Exclude MacOS attribute files.
 .DS_Store
+
+# Exclude IDE files.
+.idea/
\ No newline at end of file
diff --git a/widgets/heatmap/heatmap.go b/widgets/heatmap/heatmap.go
index 9b00c0a..b262489 100644
--- a/widgets/heatmap/heatmap.go
+++ b/widgets/heatmap/heatmap.go
@@ -20,7 +20,6 @@ import (
 	"fmt"
 	"image"
 	"math"
-	"sort"
 	"sync"
 
 	"github.com/mum4k/termdash/cell"
@@ -89,36 +88,31 @@ func NewHeatMap(opts ...Option) (*HeatMap, error) {
 	}, nil
 }
 
-// SetColumns sets the HeatMap's values, min and max values.
-func (hp *HeatMap) SetColumns(values map[string][]int64) {
+// SetColumns sets the HeatMap's X-Labels, values, min and max values.
+func (hp *HeatMap) SetColumns(xLabels []string, values map[string][]int64) error {
 	hp.mu.Lock()
 	defer hp.mu.Unlock()
 
-	var minMaxValues []int64
-
-	// The iteration order of map is uncertain, so the keys must be sorted explicitly.
-	var names []string
-	for name := range values {
-		names = append(names, name)
+	if len(xLabels) != len(values) {
+		return errors.New("the number of x-axis labels does not match the amount of column data")
 	}
-	sort.Strings(names)
 
 	// Clear XLabels and columns.
-	if len(hp.XLabels) > 0 {
-		hp.XLabels = hp.XLabels[:0]
-	}
-	hp.columns = make(map[string]*columnValues)
-
-	for _, name := range names {
-		cv := newColumnValues(values[name])
-		hp.columns[name] = cv
-		hp.XLabels = append(hp.XLabels, name)
+	hp.XLabels = hp.XLabels[:0]
+	hp.columns = make(map[string]*columnValues, len(xLabels))
+	hp.XLabels = append(hp.XLabels, xLabels...)
 
+	var minMaxValues []int64
+	for _, label := range xLabels {
+		cv := newColumnValues(values[label])
+		hp.columns[label] = cv
 		minMaxValues = append(minMaxValues, cv.Min)
 		minMaxValues = append(minMaxValues, cv.Max)
 	}
 
 	hp.MinValue, hp.MaxValue = minMax(minMaxValues)
+
+	return nil
 }
 
 // SetYLabels sets HeatMap's Y-Labels.
@@ -127,10 +121,7 @@ func (hp *HeatMap) SetYLabels(labels []string) {
 	defer hp.mu.Unlock()
 
 	// Clear YLabels.
-	if len(hp.YLabels) > 0 {
-		hp.YLabels = hp.YLabels[:0]
-	}
-
+	hp.YLabels = hp.YLabels[:0]
 	hp.YLabels = append(hp.YLabels, labels...)
 
 	// Reverse the array.
diff --git a/widgets/heatmap/heatmapdemo/heatmapdemo.go b/widgets/heatmap/heatmapdemo/heatmapdemo.go
index f67295a..b749a96 100644
--- a/widgets/heatmap/heatmapdemo/heatmapdemo.go
+++ b/widgets/heatmap/heatmapdemo/heatmapdemo.go
@@ -15,3 +15,79 @@
 // Binary heatmapdemo displays a heatmap widget.
 // Exist when 'q' is pressed.
 package main
+
+import (
+	"context"
+	"github.com/mum4k/termdash"
+	"github.com/mum4k/termdash/container"
+	"github.com/mum4k/termdash/linestyle"
+	"github.com/mum4k/termdash/terminal/termbox"
+	"github.com/mum4k/termdash/terminal/terminalapi"
+	"github.com/mum4k/termdash/widgets/heatmap"
+)
+
+func main() {
+	xLabels := []string{
+		"12:00",
+		"12:05",
+		"12:10",
+		"12:15",
+		"12:20",
+	}
+	yLabels := []string{
+		"10",
+		"20",
+		"30",
+		"40",
+		"50",
+		"60",
+		"70",
+		"80",
+		"90",
+		"100",
+	}
+	values := map[string][]int64{
+		"12:00": {10, 20, 30, 40, 50, 50, 40, 30, 20, 10},
+		"12:05": {50, 40, 30, 20, 10, 10, 20, 30, 40, 50},
+		"12:10": {10, 20, 30, 40, 50, 50, 40, 30, 20, 10},
+		"12:15": {50, 40, 30, 20, 10, 10, 20, 30, 40, 50},
+		"12:20": {10, 20, 30, 40, 50, 50, 40, 30, 0, 0},
+	}
+
+	t, err := termbox.New()
+	if err != nil {
+		panic(err)
+	}
+	defer t.Close()
+
+	hp, err := heatmap.NewHeatMap()
+	if err != nil {
+		panic(err)
+	}
+	if err := hp.SetColumns(xLabels, values); err != nil {
+		panic(err)
+	}
+	hp.SetYLabels(yLabels)
+
+	c, err := container.New(
+		t,
+		container.Border(linestyle.Light),
+		container.BorderTitle("PRESS Q TO QUIT"),
+		container.PlaceWidget(hp),
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	quitter := func(k *terminalapi.Keyboard) {
+		if k.Key == 'q' || k.Key == 'Q' {
+			cancel()
+		}
+	}
+
+	if err := termdash.Run(ctx, t, c, termdash.KeyboardSubscriber(quitter)); err != nil {
+		panic(err)
+	}
+}