diff --git a/src/Uno.UI/UI/Xaml/Media/Imaging/WriteableBitmap.cs b/src/Uno.UI/UI/Xaml/Media/Imaging/WriteableBitmap.cs
index 1fa0c5b9d6a5..9a1278210914 100644
--- a/src/Uno.UI/UI/Xaml/Media/Imaging/WriteableBitmap.cs
+++ b/src/Uno.UI/UI/Xaml/Media/Imaging/WriteableBitmap.cs
@@ -14,7 +14,11 @@ public partial class WriteableBitmap : BitmapSource
 
 		public WriteableBitmap(int pixelWidth, int pixelHeight) : base()
 		{
-			_buffer = new UwpBuffer((uint)(pixelWidth * pixelHeight * 4));
+			var pixelsBufferSize = (uint)(pixelWidth * pixelHeight * 4);
+			_buffer = new UwpBuffer(pixelsBufferSize)
+			{
+				Length = pixelsBufferSize
+			};
 
 			PixelWidth = pixelWidth;
 			PixelHeight = pixelHeight;