diff --git a/go.mod b/go.mod
index da55071..5940f4f 100644
--- a/go.mod
+++ b/go.mod
@@ -2,9 +2,13 @@ module github.com/bsm/redislock
 
 go 1.25
 
-require github.com/redis/go-redis/v9 v9.19.0
+require (
+	github.com/alicebob/miniredis/v2 v2.38.0
+	github.com/redis/go-redis/v9 v9.19.0
+)
 
 require (
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/yuin/gopher-lua v1.1.1 // indirect
 	go.uber.org/atomic v1.11.0 // indirect
 )
diff --git a/go.sum b/go.sum
index 41952ed..d5fb47e 100644
--- a/go.sum
+++ b/go.sum
@@ -1,3 +1,5 @@
+github.com/alicebob/miniredis/v2 v2.38.0 h1:nZAzCR+Lj+Vxk4ZXzm2NuKq2O33RXj1XxJ2e2uP9jiw=
+github.com/alicebob/miniredis/v2 v2.38.0/go.mod h1:TcL7YfarKPGDAthEtl5NBeHZfeUQj6OXMm/+iu5cLMM=
 github.com/bsm/ginkgo/v2 v2.12.0 h1:Ny8MWAHyOepLGlLKYmXG4IEkioBysk6GpaRTLC8zwWs=
 github.com/bsm/ginkgo/v2 v2.12.0/go.mod h1:SwYbGRRDovPVboqFv0tPTcG1sN61LM1Z4ARdbAV9g4c=
 github.com/bsm/gomega v1.27.10 h1:yeMWxP2pV2fG3FgAODIY8EiRE3dy0aeFYt4l7wh6yKA=
@@ -14,6 +16,8 @@ github.com/redis/go-redis/v9 v9.19.0 h1:XPVaaPSnG6RhYf7p+rmSa9zZfeVAnWsH5h3lxthO
 github.com/redis/go-redis/v9 v9.19.0/go.mod h1:v/M13XI1PVCDcm01VtPFOADfZtHf8YW3baQf57KlIkA=
 github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/yuin/gopher-lua v1.1.1 h1:kYKnWBjvbNP4XLT3+bPEwAXJx262OhaHDWDVOPjL46M=
+github.com/yuin/gopher-lua v1.1.1/go.mod h1:GBR0iDaNXjAgGg9zfCvksxSRnQx76gclCIb7kdAd1Pw=
 github.com/zeebo/xxh3 v1.1.0 h1:s7DLGDK45Dyfg7++yxI0khrfwq9661w9EN78eP/UZVs=
 github.com/zeebo/xxh3 v1.1.0/go.mod h1:IisAie1LELR4xhVinxWS5+zf1lA4p0MW4T+w+W07F5s=
 go.uber.org/atomic v1.11.0 h1:ZvwS0R+56ePWxUNi+Atn9dWONBPp/AUETXlHW0DxSjE=
diff --git a/refresh_test.go b/refresh_test.go
new file mode 100644
index 0000000..e4dcbc0
--- /dev/null
+++ b/refresh_test.go
@@ -0,0 +1,294 @@
+package redislock
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/alicebob/miniredis/v2"
+	"github.com/redis/go-redis/v9"
+)
+
+const loadingErr = "LOADING Redis is loading the dataset in memory"
+
+func setupMiniRedis(t *testing.T) (*miniredis.Miniredis, *redis.Client) {
+	t.Helper()
+	mr, err := miniredis.Run()
+	if err != nil {
+		t.Fatal(err)
+	}
+	rc := redis.NewClient(&redis.Options{Addr: mr.Addr()})
+	t.Cleanup(func() { rc.Close(); mr.Close() })
+	return mr, rc
+}
+
+func setLock(t *testing.T, rc *redis.Client, keys []string, val string, ttl time.Duration) *Lock {
+	t.Helper()
+	for _, k := range keys {
+		if err := rc.Set(t.Context(), k, val, ttl).Err(); err != nil {
+			t.Fatal(err)
+		}
+	}
+	return &Lock{Client: &Client{client: rc}, keys: keys, value: val, tokenLen: len(val)}
+}
+
+func assertTTL(t *testing.T, rc *redis.Client, key string, lo, hi time.Duration) {
+	t.Helper()
+	d, err := rc.PTTL(t.Context(), key).Result()
+	if err != nil || d < lo || d > hi {
+		t.Fatalf("key %s ttl %v, want [%v,%v], err=%v", key, d, lo, hi, err)
+	}
+}
+
+func refreshCtx(t *testing.T, ttl time.Duration) context.Context {
+	if ttl > 0 {
+		return t.Context()
+	}
+	ctx, cancel := context.WithTimeout(t.Context(), time.Second)
+	t.Cleanup(cancel)
+	return ctx
+}
+
+// setRedisErrors enables miniredis error injection. errFor > 0 auto-clears after that
+// duration; errFor < 0 stays until cleanup. The returned func stops any timer and
+// clears the error — call it before the Miniredis instance is closed.
+func setRedisErrors(mr *miniredis.Miniredis, errFor time.Duration) (cleanup func()) {
+	mr.SetError(loadingErr)
+	var timer *time.Timer
+	if errFor > 0 {
+		timer = time.AfterFunc(errFor, func() { mr.SetError("") })
+	}
+	return func() {
+		if timer != nil {
+			timer.Stop()
+		}
+		mr.SetError("")
+	}
+}
+
+type refreshEnv struct {
+	t  *testing.T
+	mr *miniredis.Miniredis
+	rc *redis.Client
+}
+
+type refreshCase struct {
+	name    string
+	setup   func(refreshEnv) *Lock
+	ttl     time.Duration
+	opt     *Options
+	errFor  time.Duration // 0=off, >0=brief, <0=persistent
+	wantErr func(error) bool
+	verify  func(refreshEnv)
+}
+
+func wantOK(err error) bool          { return err == nil }
+func wantNotObtained(err error) bool { return errors.Is(err, ErrNotObtained) }
+func wantLoading(err error) bool {
+	return err != nil && strings.Contains(err.Error(), "LOADING")
+}
+
+func runRefreshCase(t *testing.T, tc refreshCase) {
+	t.Helper()
+	mr, rc := setupMiniRedis(t)
+	env := refreshEnv{t: t, mr: mr, rc: rc}
+
+	lock := tc.setup(env)
+	if tc.errFor != 0 {
+		defer setRedisErrors(mr, tc.errFor)()
+	}
+
+	err := lock.Refresh(refreshCtx(t, tc.ttl), tc.ttl, tc.opt)
+
+	want := tc.wantErr
+	if want == nil {
+		want = wantOK
+	}
+	if !want(err) {
+		t.Fatalf("%s: refresh error %v", tc.name, err)
+	}
+	if wantOK(err) && tc.verify != nil {
+		tc.verify(env)
+	}
+}
+
+func setupFreshLock(e refreshEnv) *Lock {
+	return setLock(e.t, e.rc, []string{"k"}, "v", time.Hour)
+}
+
+func setupExpiredLock(e refreshEnv) *Lock {
+	l := setLock(e.t, e.rc, []string{"k"}, "v", time.Millisecond)
+	e.mr.FastForward(10 * time.Millisecond)
+	return l
+}
+
+func verifyTTL(key string, lo, hi time.Duration) func(refreshEnv) {
+	return func(e refreshEnv) { assertTTL(e.t, e.rc, key, lo, hi) }
+}
+
+func verifyKeyGone(forward time.Duration) func(refreshEnv) {
+	return func(e refreshEnv) {
+		e.mr.FastForward(forward)
+		n, err := e.rc.Exists(e.t.Context(), "k").Result()
+		if err != nil || n != 0 {
+			e.t.Fatalf("key still exists: n=%d err=%v", n, err)
+		}
+	}
+}
+
+func TestRefresh(t *testing.T) {
+	linear1ms := LinearBackoff(time.Millisecond)
+	retry3 := &Options{RetryStrategy: LimitRetry(linear1ms, 3)}
+	retry5 := &Options{RetryStrategy: LimitRetry(linear1ms, 5)}
+	retry2 := &Options{RetryStrategy: LimitRetry(linear1ms, 2)}
+	backoff200ms := &Options{RetryStrategy: LinearBackoff(200 * time.Millisecond)}
+
+	cases := []refreshCase{
+		{name: "nil receiver", setup: func(e refreshEnv) *Lock { return nil }, ttl: time.Minute, wantErr: wantNotObtained},
+		{
+			name: "success sets TTL", setup: setupFreshLock, ttl: time.Minute,
+			verify: verifyTTL("k", 59*time.Second, time.Minute),
+		},
+		{
+			name:  "extends TTL",
+			setup: func(e refreshEnv) *Lock { return setLock(e.t, e.rc, []string{"k"}, "v", time.Minute) },
+			ttl:   time.Hour, opt: &Options{}, verify: verifyTTL("k", 59*time.Minute, time.Hour),
+		},
+		{name: "expired lock", setup: setupExpiredLock, ttl: time.Minute, wantErr: wantNotObtained},
+		{name: "expired with retry", setup: setupExpiredLock, ttl: time.Minute, opt: retry3, wantErr: wantNotObtained},
+		{
+			name: "value mismatch",
+			setup: func(e refreshEnv) *Lock {
+				l := setLock(e.t, e.rc, []string{"k"}, "v", time.Hour)
+				e.rc.Set(e.t.Context(), "k", "other", time.Hour)
+				return l
+			},
+			ttl: time.Minute, wantErr: wantNotObtained,
+		},
+		{
+			name: "deleted key",
+			setup: func(e refreshEnv) *Lock {
+				l := setLock(e.t, e.rc, []string{"k"}, "v", time.Hour)
+				e.rc.Del(e.t.Context(), "k")
+				return l
+			},
+			ttl: time.Minute, wantErr: wantNotObtained,
+		},
+		{
+			name: "sequential refreshes", setup: setupFreshLock, ttl: 30 * time.Second,
+			verify: func(e refreshEnv) {
+				verifyTTL("k", 29*time.Second, 30*time.Second)(e)
+				l := &Lock{Client: &Client{client: e.rc}, keys: []string{"k"}, value: "v", tokenLen: 1}
+				if err := l.Refresh(e.t.Context(), 2*time.Minute, nil); err != nil {
+					e.t.Fatal(err)
+				}
+				verifyTTL("k", 119*time.Second, 2*time.Minute)(e)
+			},
+		},
+		{
+			name: "preserves value", setup: func(e refreshEnv) *Lock {
+				return setLock(e.t, e.rc, []string{"k"}, "tok+meta", time.Hour)
+			},
+			ttl: time.Minute,
+			verify: func(e refreshEnv) {
+				v, err := e.rc.Get(e.t.Context(), "k").Result()
+				if err != nil || v != "tok+meta" {
+					e.t.Fatalf("got %q err=%v", v, err)
+				}
+			},
+		},
+		{name: "small TTL expires", setup: setupFreshLock, ttl: time.Millisecond, verify: verifyKeyGone(10 * time.Millisecond)},
+		{name: "zero TTL expires", setup: setupFreshLock, ttl: 0, verify: verifyKeyGone(time.Millisecond)},
+		{
+			name: "multi-key missing",
+			setup: func(e refreshEnv) *Lock {
+				l := setLock(e.t, e.rc, []string{"a", "b"}, "v", time.Hour)
+				e.rc.Del(e.t.Context(), "b")
+				return l
+			},
+			ttl: time.Minute, wantErr: wantNotObtained,
+		},
+		{
+			name: "multi-key wrong value",
+			setup: func(e refreshEnv) *Lock {
+				l := setLock(e.t, e.rc, []string{"a", "b"}, "v", time.Hour)
+				e.rc.Set(e.t.Context(), "a", "x", time.Hour)
+				return l
+			},
+			ttl: time.Minute, wantErr: wantNotObtained,
+		},
+		{
+			name: "ctx deadline during backoff", setup: setupExpiredLock,
+			ttl: time.Minute, opt: backoff200ms, wantErr: wantNotObtained,
+		},
+		{
+			name: "recovers from transient errors", setup: setupFreshLock,
+			ttl: time.Minute, opt: retry5, errFor: 5 * time.Millisecond,
+			verify: verifyTTL("k", 59*time.Second, time.Minute),
+		},
+		{
+			name: "exhausts retries returns last error", setup: setupFreshLock,
+			ttl: time.Minute, opt: retry2, errFor: -1, wantErr: wantLoading,
+		},
+		{
+			name: "NoRetry returns redis error", setup: setupFreshLock,
+			ttl: time.Minute, opt: &Options{RetryStrategy: NoRetry()}, errFor: -1, wantErr: wantLoading,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) { runRefreshCase(t, tc) })
+	}
+
+	t.Run("ctx cancelled during retry", func(t *testing.T) {
+		mr, rc := setupMiniRedis(t)
+		lock := setLock(t, rc, []string{"k"}, "v", time.Hour)
+		ctx, cancel := context.WithCancel(t.Context())
+		defer cancel()
+		mr.SetError(loadingErr)
+		timer := time.AfterFunc(3*time.Millisecond, func() { cancel(); mr.SetError("") })
+		defer func() {
+			timer.Stop()
+			mr.SetError("")
+		}()
+		err := lock.Refresh(ctx, time.Minute, &Options{RetryStrategy: linear1ms})
+		if !errors.Is(err, context.Canceled) {
+			t.Fatalf("got %v", err)
+		}
+	})
+
+	t.Run("NoRetry calls NextBackoff once on transient failure", func(t *testing.T) {
+		mr, rc := setupMiniRedis(t)
+		lock := setLock(t, rc, []string{"k"}, "v", time.Hour)
+		defer setRedisErrors(mr, -1)()
+		calls := 0
+		spy := &spyRetry{inner: NoRetry(), onCall: func() { calls++ }}
+		err := lock.Refresh(t.Context(), time.Minute, &Options{RetryStrategy: spy})
+		if calls != 1 || !wantLoading(err) {
+			t.Fatalf("calls=%d err=%v", calls, err)
+		}
+	})
+
+	t.Run("success never calls NextBackoff", func(t *testing.T) {
+		_, rc := setupMiniRedis(t)
+		lock := setLock(t, rc, []string{"k"}, "v", time.Hour)
+		calls := 0
+		spy := &spyRetry{inner: linear1ms, onCall: func() { calls++ }}
+		err := lock.Refresh(t.Context(), time.Minute, &Options{RetryStrategy: spy})
+		if err != nil || calls != 0 {
+			t.Fatalf("calls=%d err=%v", calls, err)
+		}
+	})
+}
+
+type spyRetry struct {
+	inner  RetryStrategy
+	onCall func()
+}
+
+func (s *spyRetry) NextBackoff() time.Duration {
+	s.onCall()
+	return s.inner.NextBackoff()
+}