diff --git a/diff/lcow/lcow.go b/diff/lcow/lcow.go
index 05ce3fb21..4c5d74ca3 100644
--- a/diff/lcow/lcow.go
+++ b/diff/lcow/lcow.go
@@ -178,7 +178,7 @@ func (s windowsLcowDiff) Apply(ctx context.Context, desc ocispec.Descriptor, mou
 // Compare creates a diff between the given mounts and uploads the result
 // to the content store.
 func (s windowsLcowDiff) Compare(ctx context.Context, lower, upper []mount.Mount, opts ...diff.Opt) (d ocispec.Descriptor, err error) {
-	return emptyDesc, errdefs.ErrNotImplemented
+	return emptyDesc, errors.Wrap(errdefs.ErrNotImplemented, "windowsLcowDiff does not implement Compare method")
 }
 
 type readCounter struct {
diff --git a/diff/windows/windows.go b/diff/windows/windows.go
index af193516b..3de358683 100644
--- a/diff/windows/windows.go
+++ b/diff/windows/windows.go
@@ -158,7 +158,7 @@ func (s windowsDiff) Apply(ctx context.Context, desc ocispec.Descriptor, mounts
 // Compare creates a diff between the given mounts and uploads the result
 // to the content store.
 func (s windowsDiff) Compare(ctx context.Context, lower, upper []mount.Mount, opts ...diff.Opt) (d ocispec.Descriptor, err error) {
-	return emptyDesc, errdefs.ErrNotImplemented
+	return emptyDesc, errors.Wrap(errdefs.ErrNotImplemented, "windowsDiff does not implement Compare method")
 }
 
 type readCounter struct {
@@ -181,7 +181,7 @@ func mountsToLayerAndParents(mounts []mount.Mount) (string, []string, error) {
 		// This is a special case error. When this is received the diff service
 		// will attempt the next differ in the chain which for Windows is the
 		// lcow differ that we want.
-		return "", nil, errdefs.ErrNotImplemented
+		return "", nil, errors.Wrapf(errdefs.ErrNotImplemented, "windowsDiff does not support layer type %s", mnt.Type)
 	}
 
 	parentLayerPaths, err := mnt.GetParentPaths()
diff --git a/images/mediatypes.go b/images/mediatypes.go
index 2f47b0e68..a0005d4e2 100644
--- a/images/mediatypes.go
+++ b/images/mediatypes.go
@@ -23,6 +23,7 @@ import (
 
 	"github.com/containerd/containerd/errdefs"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
 )
 
 // mediatype definitions for image components handled in containerd.
@@ -81,7 +82,7 @@ func DiffCompression(ctx context.Context, mediaType string) (string, error) {
 		}
 		return "", nil
 	default:
-		return "", errdefs.ErrNotImplemented
+		return "", errors.Wrapf(errdefs.ErrNotImplemented, "unrecognised mediatype %s", mediaType)
 	}
 }