diff --git a/bin/stitch/stitched-image-cache.go b/bin/stitch/stitched-image-cache.go
index fd68714..729016e 100644
--- a/bin/stitch/stitched-image-cache.go
+++ b/bin/stitch/stitched-image-cache.go
@@ -1,4 +1,4 @@
-// Copyright (c) 2022-2023 David Vogel
+// Copyright (c) 2022-2024 David Vogel
 //
 // This software is released under the MIT License.
 // https://opensource.org/licenses/MIT
@@ -8,6 +8,7 @@ package main
 import (
 	"image"
 	"image/color"
+	"image/draw"
 	"runtime"
 	"sync"
 )
@@ -69,7 +70,9 @@ func (sic *StitchedImageCache) Regenerate() *image.RGBA {
 
 	si := sic.stitchedImage
 
+	// Create new image with default background color.
 	cacheImage := image.NewRGBA(sic.rect)
+	draw.Draw(cacheImage, cacheImage.Bounds(), &image.Uniform{colorBackground}, cacheImage.Bounds().Min, draw.Src)
 
 	// List of tiles that intersect with the to be generated cache image.
 	intersectingTiles := []*ImageTile{}
diff --git a/bin/stitch/stitched-image.go b/bin/stitch/stitched-image.go
index c3d0914..a9b2d05 100644
--- a/bin/stitch/stitched-image.go
+++ b/bin/stitch/stitched-image.go
@@ -1,4 +1,4 @@
-// Copyright (c) 2022-2023 David Vogel
+// Copyright (c) 2022-2024 David Vogel
 //
 // This software is released under the MIT License.
 // https://opensource.org/licenses/MIT
@@ -13,6 +13,10 @@ import (
 	"time"
 )
 
+// The default background color.
+// We use a non transparent black.
+var colorBackground = color.RGBA{0, 0, 0, 255}
+
 // StitchedImageCacheGridSize defines the worker chunk size when the cache image is regenerated.
 var StitchedImageCacheGridSize = 256
 
@@ -116,7 +120,7 @@ func (si *StitchedImage) RGBAAt(x, y int) color.RGBA {
 	// Determine the cache rowIndex index.
 	rowIndex := (y + si.cacheRowYOffset) / si.cacheRowHeight
 	if rowIndex < 0 || rowIndex >= len(si.cacheRows) {
-		return color.RGBA{}
+		return colorBackground
 	}
 
 	// Check if we advanced/changed the row index.
diff --git a/bin/stitch/sub-stitched-image.go b/bin/stitch/sub-stitched-image.go
index 3eca3fe..f147845 100644
--- a/bin/stitch/sub-stitched-image.go
+++ b/bin/stitch/sub-stitched-image.go
@@ -1,4 +1,4 @@
-// Copyright (c) 2023 David Vogel
+// Copyright (c) 2023-2024 David Vogel
 //
 // This software is released under the MIT License.
 // https://opensource.org/licenses/MIT
@@ -29,7 +29,7 @@ func (s SubStitchedImage) At(x, y int) color.Color {
 func (s SubStitchedImage) RGBAAt(x, y int) color.RGBA {
 	point := image.Point{X: x, Y: y}
 	if !point.In(s.bounds) {
-		return color.RGBA{}
+		return colorBackground
 	}
 
 	return s.StitchedImage.RGBAAt(x, y)