@@ -2,6 +2,7 @@ package calendar
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"io/fs"
@@ -10,8 +11,9 @@ "os"
 	"slices"
 	"time"
 
+	"github.com/Southclaws/fault"
+	"github.com/Southclaws/fault/fmsg"
 	ical "github.com/arran4/golang-ical"
-	"gitlab.com/tozd/go/errors"
 	"go.alanpearce.eu/x/log"
 
 	"go.alanpearce.eu/homestead/internal/cache"
@@ -71,7 +73,7 @@ }
 
 	stat, err := cache.Root.Stat(Filename)
 	if err != nil && !errors.Is(err, fs.ErrNotExist) {
-		return false, errors.WithMessage(err, "could not stat calendar file")
+		return false, fault.Wrap(err, fmsg.With("could not stat calendar file"))
 	}
 
 	return stat != nil && time.Since(stat.ModTime()) < Refresh && stat.Size() > 0, nil
@@ -99,52 +101,52 @@ c.Calendar, err = ical.ParseCalendar(f)
 	if err != nil {
 		c.log.Warn("error parsing calendar", "error", err)
 
-		return errors.WithMessage(err, "could not parse calendar")
+		return fault.Wrap(err, fmsg.With("could not parse calendar"))
 	}
 
 	return err
 }
 
-func (c *Calendar) open() (*os.File, errors.E) {
+func (c *Calendar) open() (*os.File, error) {
 	f, err := cache.Root.Open(Filename)
 	if err != nil {
-		return nil, errors.WithMessage(err, "could not open calendar file")
+		return nil, fault.Wrap(err, fmsg.With("could not open calendar file"))
 	}
 
 	return f, nil
 }
 
-func (c *Calendar) fetch(ctx context.Context) errors.E {
+func (c *Calendar) fetch(ctx context.Context) error {
 	c.log.Debug("fetching calendar", "url", c.opts.URL.String())
 
 	f, err := cache.Root.OpenFile(Filename, os.O_RDWR|os.O_CREATE, 0o600)
 	if err != nil {
-		return errors.WithMessage(err, "could not create temp file")
+		return fault.Wrap(err, fmsg.With("could not create temp file"))
 	}
 	defer f.Close()
 
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.opts.URL.String(), nil)
 	if err != nil {
-		return errors.WithMessage(err, "could not create request")
+		return fault.Wrap(err, fmsg.With("could not create request"))
 	}
 
 	res, err := c.client.Do(req)
 	if err != nil {
-		return errors.WithMessage(err, "could not fetch calendar")
+		return fault.Wrap(err, fmsg.With("could not fetch calendar"))
 	}
 	defer res.Body.Close()
 
 	if res.StatusCode != http.StatusOK {
-		return errors.New(fmt.Sprintf("unexpected status code %d", res.StatusCode))
+		return fault.New(fmt.Sprintf("unexpected status code %d", res.StatusCode))
 	}
 
 	if _, err := io.Copy(f, res.Body); err != nil {
-		return errors.WithMessage(err, "could not write calendar to file")
+		return fault.Wrap(err, fmsg.With("could not write calendar to file"))
 	}
 
 	err = f.Sync()
 	if err != nil {
-		return errors.WithMessage(err, "could not sync file")
+		return fault.Wrap(err, fmsg.With("could not sync file"))
 	}
 
 	return nil
@@ -152,7 +154,7 @@ }
 
 func (c *Calendar) EventsBetween(from time.Time, to time.Time) ([]*Busy, error) {
 	if c.Calendar == nil {
-		return nil, errors.New("calendar not initialised")
+		return nil, fault.New("calendar not initialised")
 	}
 
 	in := c.Busys()
@@ -235,7 +237,7 @@ cd := &CalendarDate{Date: date}
 
 		evs, err := c.EventsBetween(date.Add(1*time.Second), date.EndOfDay().Time)
 		if err != nil {
-			return nil, errors.WithMessage(err, "could not get events")
+			return nil, fault.Wrap(err, fmsg.With("could not get events"))
 		}
 
 		for _, ev := range evs {