diff --git a/src/ImageSharp/Formats/Png/PngDecoderCore.cs b/src/ImageSharp/Formats/Png/PngDecoderCore.cs
index 3bc2ccf492..dd2ce9eb14 100644
--- a/src/ImageSharp/Formats/Png/PngDecoderCore.cs
+++ b/src/ImageSharp/Formats/Png/PngDecoderCore.cs
@@ -648,7 +648,8 @@ internal sealed class PngDecoderCore : IImageDecoderInternals
     {
         frame = image.Frames.AddFrame(previousFrame ?? image.Frames.RootFrame);
 
-        // If restoring to before first frame, restore to background. Same if first frame (previousFrameControl null).
+        // If the first `fcTL` chunk uses a `dispose_op` of APNG_DISPOSE_OP_PREVIOUS it should be treated as APNG_DISPOSE_OP_BACKGROUND.
+        // So, if restoring to before first frame, clear entire area. Same if first frame (previousFrameControl null).
         if (previousFrameControl == null || (previousFrame is null && previousFrameControl.Value.DisposeOperation == PngDisposalMethod.RestoreToPrevious))
         {
             Buffer2DRegion<TPixel> pixelRegion = frame.PixelBuffer.GetRegion();