diff --git a/pkg/enchantrix/sigils.go b/pkg/enchantrix/sigils.go
index 60c0391..6fc5cfa 100644
--- a/pkg/enchantrix/sigils.go
+++ b/pkg/enchantrix/sigils.go
@@ -73,12 +73,18 @@ func (s *Base64Sigil) Out(data []byte) ([]byte, error) {
 }
 
 // GzipSigil is a Sigil that compresses/decompresses data using gzip.
-type GzipSigil struct{}
+type GzipSigil struct {
+	writer io.Writer
+}
 
 // In compresses the data using gzip.
 func (s *GzipSigil) In(data []byte) ([]byte, error) {
 	var b bytes.Buffer
-	gz := gzip.NewWriter(&b)
+	w := s.writer
+	if w == nil {
+		w = &b
+	}
+	gz := gzip.NewWriter(w)
 	if _, err := gz.Write(data); err != nil {
 		return nil, err
 	}
diff --git a/pkg/enchantrix/sigils_test.go b/pkg/enchantrix/sigils_test.go
index defb616..c191bd2 100644
--- a/pkg/enchantrix/sigils_test.go
+++ b/pkg/enchantrix/sigils_test.go
@@ -2,11 +2,32 @@ package enchantrix
 
 import (
 	"encoding/hex"
+	"errors"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 )
 
+// mockWriter is a writer that fails on Write
+type mockWriter struct{}
+
+func (m *mockWriter) Write(p []byte) (n int, err error) {
+	return 0, errors.New("write error")
+}
+
+// failOnSecondWrite is a writer that fails on the second write call.
+type failOnSecondWrite struct {
+	callCount int
+}
+
+func (m *failOnSecondWrite) Write(p []byte) (n int, err error) {
+	m.callCount++
+	if m.callCount > 1 {
+		return 0, errors.New("second write failed")
+	}
+	return len(p), nil
+}
+
 func TestReverseSigil(t *testing.T) {
 	s := &ReverseSigil{}
 	data := []byte("hello")
@@ -67,6 +88,16 @@ func TestGzipSigil(t *testing.T) {
 	// Bad - invalid gzip data
 	_, err = s.Out([]byte("not gzip"))
 	assert.Error(t, err)
+
+	// Test writer error
+	s.writer = &mockWriter{}
+	_, err = s.In(data)
+	assert.Error(t, err)
+
+	// Test closer error
+	s.writer = &failOnSecondWrite{}
+	_, err = s.In(data)
+	assert.Error(t, err)
 }
 
 func TestJSONSigil(t *testing.T) {
@@ -83,6 +114,11 @@ func TestJSONSigil(t *testing.T) {
 	// Bad - invalid json
 	_, err = s.In([]byte("not json"))
 	assert.Error(t, err)
+
+	// Out is a no-op, so it should return the data as-is
+	outData, err := s.Out(data)
+	assert.NoError(t, err)
+	assert.Equal(t, data, outData)
 }
 
 func TestHashSigils_Good(t *testing.T) {