diff --git a/copy/compression.go b/copy/compression.go
index cfb4c8d107..1ff79c424d 100644
--- a/copy/compression.go
+++ b/copy/compression.go
@@ -46,6 +46,7 @@ type bpDetectCompressionStepData struct {
 // Returns data for other steps.
 func blobPipelineDetectCompressionStep(stream *sourceStream, srcInfo types.BlobInfo) (bpDetectCompressionStepData, error) {
 	// This requires us to “peek ahead” into the stream to read the initial part, which requires us to chain through another io.Reader returned by DetectCompression.
+	// FIXME: Detect zstd:chunked from annotations!
 	format, decompressor, reader, err := compression.DetectCompressionFormat(stream.reader) // We could skip this in some cases, but let's keep the code path uniform
 	if err != nil {
 		return bpDetectCompressionStepData{}, fmt.Errorf("reading blob %s: %w", srcInfo.Digest, err)