diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index d74cf7c..b9c4964 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -8,6 +8,8 @@ jobs:
   golangci:
     name: lint
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
     steps:
       - uses: actions/setup-go@v6
         with:
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index da1d0e5..9e8a843 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -10,6 +10,7 @@ jobs:
   test:
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
         go:
           - "1.18"
@@ -19,6 +20,7 @@ jobs:
           - "1.22"
           - "1.23"
           - "1.24"
+          - "1.25"
           - "1.x"
     steps:
       - uses: actions/checkout@v5
diff --git a/Makefile b/Makefile
index 8badbda..ae6d5e6 100644
--- a/Makefile
+++ b/Makefile
@@ -3,9 +3,9 @@ build:
 	go build -v ./...
 
 test:
-	go test -race -v ./...
+	go test -race ./...
 watch-test:
-	reflex -t 50ms -s -- sh -c 'gotest -race -v ./...'
+	reflex -t 50ms -s -- sh -c 'gotest -race ./...'
 
 bench:
 	go test -benchmem -count 3 -bench ./...
diff --git a/channel_test.go b/channel_test.go
index 6157219..398a95a 100644
--- a/channel_test.go
+++ b/channel_test.go
@@ -98,7 +98,7 @@ func TestChannelDispatcher(t *testing.T) {
 
 func TestDispatchingStrategyRoundRobin(t *testing.T) {
 	t.Parallel()
-	testWithTimeout(t, 10*time.Millisecond)
+	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
 	children := createChannels[int](3, 2)
@@ -113,7 +113,7 @@ func TestDispatchingStrategyRoundRobin(t *testing.T) {
 
 func TestDispatchingStrategyRandom(t *testing.T) {
 	t.Parallel()
-	testWithTimeout(t, 10*time.Millisecond)
+	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
 	children := createChannels[int](2, 2)
@@ -129,7 +129,7 @@ func TestDispatchingStrategyRandom(t *testing.T) {
 
 func TestDispatchingStrategyWeightedRandom(t *testing.T) {
 	t.Parallel()
-	testWithTimeout(t, 10*time.Millisecond)
+	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
 	children := createChannels[int](2, 2)
@@ -147,7 +147,7 @@ func TestDispatchingStrategyWeightedRandom(t *testing.T) {
 
 func TestDispatchingStrategyFirst(t *testing.T) {
 	t.Parallel()
-	testWithTimeout(t, 10*time.Millisecond)
+	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
 	children := createChannels[int](2, 2)
@@ -163,7 +163,7 @@ func TestDispatchingStrategyFirst(t *testing.T) {
 
 func TestDispatchingStrategyLeast(t *testing.T) {
 	t.Parallel()
-	testWithTimeout(t, 10*time.Millisecond)
+	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
 	children := createChannels[int](2, 2)
@@ -183,7 +183,7 @@ func TestDispatchingStrategyLeast(t *testing.T) {
 
 func TestDispatchingStrategyMost(t *testing.T) {
 	t.Parallel()
-	testWithTimeout(t, 10*time.Millisecond)
+	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
 	children := createChannels[int](2, 2)
@@ -203,7 +203,7 @@ func TestDispatchingStrategyMost(t *testing.T) {
 
 func TestSliceToChannel(t *testing.T) {
 	t.Parallel()
-	testWithTimeout(t, 10*time.Millisecond)
+	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
 	ch := SliceToChannel(2, []int{1, 2, 3})
@@ -224,7 +224,7 @@ func TestSliceToChannel(t *testing.T) {
 
 func TestChannelToSlice(t *testing.T) {
 	t.Parallel()
-	testWithTimeout(t, 10*time.Millisecond)
+	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
 	ch := SliceToChannel(2, []int{1, 2, 3})
@@ -235,7 +235,7 @@ func TestChannelToSlice(t *testing.T) {
 
 func TestGenerate(t *testing.T) {
 	t.Parallel()
-	testWithTimeout(t, 10*time.Millisecond)
+	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
 	generator := func(yield func(int)) {
@@ -257,7 +257,7 @@ func TestGenerate(t *testing.T) {
 
 func TestBuffer(t *testing.T) {
 	t.Parallel()
-	testWithTimeout(t, 10*time.Millisecond)
+	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
 	ch := SliceToChannel(2, []int{1, 2, 3})
@@ -277,8 +277,8 @@ func TestBuffer(t *testing.T) {
 	is.False(ok3)
 }
 
-func TestBufferWithContext(t *testing.T) {
-	t.Parallel()
+func TestBufferWithContext(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	testWithTimeout(t, 200*time.Millisecond)
 	is := assert.New(t)
 
@@ -313,47 +313,60 @@ func TestBufferWithContext(t *testing.T) {
 	is.True(ok2)
 }
 
-func TestBufferWithTimeout(t *testing.T) {
-	t.Parallel()
-	testWithTimeout(t, 200*time.Millisecond)
+func TestBufferWithTimeout(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
+	testWithTimeout(t, 2000*time.Millisecond)
 	is := assert.New(t)
 
-	generator := func(yield func(int)) {
-		for i := 0; i < 5; i++ {
-			yield(i)
-			time.Sleep(10 * time.Millisecond)
+	generator := func(n ...int) func(yield func(int)) {
+		return func(yield func(int)) {
+			for i := 0; i < len(n); i++ {
+				yield(n[i])
+				time.Sleep(100 * time.Millisecond)
+			}
 		}
 	}
-	ch := Generator(0, generator)
 
-	items1, length1, _, ok1 := BufferWithTimeout(ch, 20, 15*time.Millisecond)
+	ch := Generator(0, generator(0, 1, 2, 3, 4))
+	items1, length1, duration1, ok1 := BufferWithTimeout(ch, 20, 150*time.Millisecond)
 	is.Equal([]int{0, 1}, items1)
 	is.Equal(2, length1)
+	is.InDelta(150*time.Millisecond, duration1, float64(20*time.Millisecond))
 	is.True(ok1)
 
-	items2, length2, _, ok2 := BufferWithTimeout(ch, 20, 2*time.Millisecond)
+	items2, length2, duration2, ok2 := BufferWithTimeout(ch, 20, 10*time.Millisecond)
 	is.Empty(items2)
 	is.Zero(length2)
+	is.InDelta(10*time.Millisecond, duration2, float64(10*time.Millisecond))
 	is.True(ok2)
 
-	items3, length3, _, ok3 := BufferWithTimeout(ch, 1, 30*time.Millisecond)
+	items3, length3, duration3, ok3 := BufferWithTimeout(ch, 1, 300*time.Millisecond)
 	is.Equal([]int{2}, items3)
 	is.Equal(1, length3)
+	is.InDelta(50*time.Millisecond, duration3, float64(20*time.Millisecond))
 	is.True(ok3)
 
-	items4, length4, _, ok4 := BufferWithTimeout(ch, 2, 25*time.Millisecond)
+	items4, length4, duration4, ok4 := BufferWithTimeout(ch, 2, 250*time.Millisecond)
 	is.Equal([]int{3, 4}, items4)
 	is.Equal(2, length4)
+	is.InDelta(200*time.Millisecond, duration4, float64(50*time.Millisecond))
 	is.True(ok4)
 
-	items5, length5, _, ok5 := BufferWithTimeout(ch, 3, 25*time.Millisecond)
+	items5, length5, duration5, ok5 := BufferWithTimeout(ch, 3, 250*time.Millisecond)
 	is.Empty(items5)
 	is.Zero(length5)
+	is.InDelta(100*time.Millisecond, duration5, float64(50*time.Millisecond))
 	is.False(ok5)
+
+	items6, length6, duration6, ok6 := BufferWithTimeout(ch, 3, 250*time.Millisecond)
+	is.Empty(items6)
+	is.Zero(length6)
+	is.InDelta(1*time.Millisecond, duration6, float64(10*time.Millisecond))
+	is.False(ok6)
 }
 
-func TestFanIn(t *testing.T) {
-	t.Parallel()
+func TestFanIn(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
@@ -392,8 +405,8 @@ func TestFanIn(t *testing.T) {
 	is.Zero(msg0)
 }
 
-func TestFanOut(t *testing.T) {
-	t.Parallel()
+func TestFanOut(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
diff --git a/concurrency_test.go b/concurrency_test.go
index 887ba86..382932f 100644
--- a/concurrency_test.go
+++ b/concurrency_test.go
@@ -9,9 +9,9 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestSynchronize(t *testing.T) {
-	t.Parallel()
-	testWithTimeout(t, 100*time.Millisecond)
+func TestSynchronize(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
+	testWithTimeout(t, 1000*time.Millisecond)
 	is := assert.New(t)
 
 	// check that callbacks are not executed concurrently
@@ -25,7 +25,7 @@ func TestSynchronize(t *testing.T) {
 
 		for i := 0; i < 10; i++ {
 			go s.Do(func() {
-				time.Sleep(5 * time.Millisecond)
+				time.Sleep(50 * time.Millisecond)
 				wg.Done()
 			})
 		}
@@ -33,9 +33,7 @@ func TestSynchronize(t *testing.T) {
 		wg.Wait()
 
 		duration := time.Since(start)
-
-		is.Greater(duration, 50*time.Millisecond)
-		is.Less(duration, 60*time.Millisecond)
+		is.InDelta(500*time.Millisecond, duration, float64(40*time.Millisecond))
 	}
 
 	// check locker is locked
@@ -62,8 +60,8 @@ func TestSynchronize(t *testing.T) {
 	}
 }
 
-func TestAsync(t *testing.T) {
-	t.Parallel()
+func TestAsync(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
@@ -84,8 +82,8 @@ func TestAsync(t *testing.T) {
 	}
 }
 
-func TestAsyncX(t *testing.T) {
-	t.Parallel()
+func TestAsyncX(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	testWithTimeout(t, 100*time.Millisecond)
 	is := assert.New(t)
 
@@ -214,33 +212,29 @@ func TestAsyncX(t *testing.T) {
 	}
 }
 
-func TestWaitFor(t *testing.T) {
-	t.Parallel()
+func TestWaitFor(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 
-	testTimeout := 100 * time.Millisecond
-	longTimeout := 2 * testTimeout
-	shortTimeout := 4 * time.Millisecond
+	t.Run("exist condition works", func(t *testing.T) { //nolint:paralleltest
+		// t.Parallel()
 
-	t.Run("exist condition works", func(t *testing.T) {
-		t.Parallel()
-
-		testWithTimeout(t, testTimeout)
+		testWithTimeout(t, 300*time.Millisecond)
 		is := assert.New(t)
 
 		laterTrue := func(i int) bool {
 			return i >= 5
 		}
 
-		iter, duration, ok := WaitFor(laterTrue, longTimeout, time.Millisecond)
+		iter, duration, ok := WaitFor(laterTrue, 200*time.Millisecond, 10*time.Millisecond)
 		is.Equal(6, iter, "unexpected iteration count")
-		is.InEpsilon(6*time.Millisecond, duration, float64(500*time.Microsecond))
+		is.InDelta(60*time.Millisecond, duration, float64(5*time.Millisecond))
 		is.True(ok)
 	})
 
-	t.Run("counter is incremented", func(t *testing.T) {
-		t.Parallel()
+	t.Run("counter is incremented", func(t *testing.T) { //nolint:paralleltest
+		// t.Parallel()
 
-		testWithTimeout(t, testTimeout)
+		testWithTimeout(t, 100*time.Millisecond)
 		is := assert.New(t)
 
 		counter := 0
@@ -250,80 +244,63 @@ func TestWaitFor(t *testing.T) {
 			return false
 		}
 
-		iter, duration, ok := WaitFor(alwaysFalse, shortTimeout, 1050*time.Microsecond)
+		iter, duration, ok := WaitFor(alwaysFalse, 40*time.Millisecond, 10*time.Millisecond)
 		is.Equal(counter, iter, "unexpected iteration count")
-		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
+		is.InDelta(40*time.Millisecond, duration, float64(5*time.Millisecond))
 		is.False(ok)
 	})
 
 	alwaysTrue := func(_ int) bool { return true }
 	alwaysFalse := func(_ int) bool { return false }
 
-	t.Run("short timeout works", func(t *testing.T) {
-		t.Parallel()
+	t.Run("timeout works", func(t *testing.T) { //nolint:paralleltest
+		// t.Parallel()
 
-		testWithTimeout(t, testTimeout)
+		testWithTimeout(t, 200*time.Millisecond)
 		is := assert.New(t)
 
-		iter, duration, ok := WaitFor(alwaysFalse, shortTimeout, 10*time.Millisecond)
+		iter, duration, ok := WaitFor(alwaysFalse, 50*time.Millisecond, 100*time.Millisecond)
 		is.Zero(iter, "unexpected iteration count")
-		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
+		is.InDelta(50*time.Millisecond, duration, float64(10*time.Millisecond))
 		is.False(ok)
 	})
 
-	t.Run("timeout works", func(t *testing.T) {
-		t.Parallel()
+	t.Run("exist on first condition", func(t *testing.T) { //nolint:paralleltest
+		// t.Parallel()
 
-		testWithTimeout(t, testTimeout)
+		testWithTimeout(t, 200*time.Millisecond)
 		is := assert.New(t)
 
-		shortTimeout := 4 * time.Millisecond
-		iter, duration, ok := WaitFor(alwaysFalse, shortTimeout, 10*time.Millisecond)
-		is.Zero(iter, "unexpected iteration count")
-		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
-		is.False(ok)
-	})
-
-	t.Run("exist on first condition", func(t *testing.T) {
-		t.Parallel()
-
-		testWithTimeout(t, testTimeout)
-		is := assert.New(t)
-
-		iter, duration, ok := WaitFor(alwaysTrue, 10*time.Millisecond, time.Millisecond)
+		iter, duration, ok := WaitFor(alwaysTrue, 100*time.Millisecond, 30*time.Millisecond)
 		is.Equal(1, iter, "unexpected iteration count")
-		is.InEpsilon(time.Millisecond, duration, float64(5*time.Microsecond))
+		is.InDelta(30*time.Millisecond, duration, float64(10*time.Millisecond))
 		is.True(ok)
 	})
 }
 
-func TestWaitForWithContext(t *testing.T) {
-	t.Parallel()
+func TestWaitForWithContext(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 
-	testTimeout := 100 * time.Millisecond
-	longTimeout := 2 * testTimeout
-	shortTimeout := 4 * time.Millisecond
+	t.Run("exist condition works", func(t *testing.T) { //nolint:paralleltest
+		// t.Parallel()
 
-	t.Run("exist condition works", func(t *testing.T) {
-		t.Parallel()
-
-		testWithTimeout(t, testTimeout)
+		testWithTimeout(t, 200*time.Millisecond)
 		is := assert.New(t)
 
 		laterTrue := func(_ context.Context, i int) bool {
 			return i >= 5
 		}
 
-		iter, duration, ok := WaitForWithContext(context.Background(), laterTrue, longTimeout, time.Millisecond)
+		iter, duration, ok := WaitForWithContext(context.Background(), laterTrue, 200*time.Millisecond, 10*time.Millisecond)
 		is.Equal(6, iter, "unexpected iteration count")
-		is.InEpsilon(6*time.Millisecond, duration, float64(500*time.Microsecond))
+		is.InDelta(60*time.Millisecond, duration, float64(5*time.Millisecond))
 		is.True(ok)
 	})
 
-	t.Run("counter is incremented", func(t *testing.T) {
-		t.Parallel()
+	t.Run("counter is incremented", func(t *testing.T) { //nolint:paralleltest
+		// t.Parallel()
 
-		testWithTimeout(t, testTimeout)
+		testWithTimeout(t, 100*time.Millisecond)
 		is := assert.New(t)
 
 		counter := 0
@@ -333,81 +310,68 @@ func TestWaitForWithContext(t *testing.T) {
 			return false
 		}
 
-		iter, duration, ok := WaitForWithContext(context.Background(), alwaysFalse, shortTimeout, 1050*time.Microsecond)
+		iter, duration, ok := WaitForWithContext(context.Background(), alwaysFalse, 40*time.Millisecond, 10*time.Millisecond)
 		is.Equal(counter, iter, "unexpected iteration count")
-		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
+		is.InDelta(40*time.Millisecond, duration, float64(5*time.Millisecond))
 		is.False(ok)
 	})
 
 	alwaysTrue := func(_ context.Context, _ int) bool { return true }
 	alwaysFalse := func(_ context.Context, _ int) bool { return false }
 
-	t.Run("short timeout works", func(t *testing.T) {
-		t.Parallel()
+	t.Run("timeout works", func(t *testing.T) { //nolint:paralleltest
+		// t.Parallel()
 
-		testWithTimeout(t, testTimeout)
+		testWithTimeout(t, 200*time.Millisecond)
 		is := assert.New(t)
 
-		iter, duration, ok := WaitForWithContext(context.Background(), alwaysFalse, shortTimeout, 10*time.Millisecond)
+		iter, duration, ok := WaitForWithContext(context.Background(), alwaysFalse, 50*time.Millisecond, 100*time.Millisecond)
 		is.Zero(iter, "unexpected iteration count")
-		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
+		is.InDelta(50*time.Millisecond, duration, float64(10*time.Millisecond))
 		is.False(ok)
 	})
 
-	t.Run("timeout works", func(t *testing.T) {
-		t.Parallel()
+	t.Run("exist on first condition", func(t *testing.T) { //nolint:paralleltest
+		// t.Parallel()
 
-		testWithTimeout(t, testTimeout)
+		testWithTimeout(t, 200*time.Millisecond)
 		is := assert.New(t)
 
-		shortTimeout := 4 * time.Millisecond
-		iter, duration, ok := WaitForWithContext(context.Background(), alwaysFalse, shortTimeout, 10*time.Millisecond)
-		is.Zero(iter, "unexpected iteration count")
-		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
-		is.False(ok)
-	})
-
-	t.Run("exist on first condition", func(t *testing.T) {
-		t.Parallel()
-
-		testWithTimeout(t, testTimeout)
-		is := assert.New(t)
-
-		iter, duration, ok := WaitForWithContext(context.Background(), alwaysTrue, 10*time.Millisecond, time.Millisecond)
+		iter, duration, ok := WaitForWithContext(context.Background(), alwaysTrue, 100*time.Millisecond, 10*time.Millisecond)
 		is.Equal(1, iter, "unexpected iteration count")
-		is.InEpsilon(time.Millisecond, duration, float64(5*time.Microsecond))
+		is.InDelta(10*time.Millisecond, duration, float64(5*time.Millisecond))
 		is.True(ok)
 	})
 
-	t.Run("context cancellation stops everything", func(t *testing.T) {
-		t.Parallel()
+	t.Run("context cancellation stops everything", func(t *testing.T) { //nolint:paralleltest
+		// t.Parallel()
 
-		testWithTimeout(t, testTimeout)
+		testWithTimeout(t, 100*time.Millisecond)
 		is := assert.New(t)
 
-		expiringCtx, clean := context.WithTimeout(context.Background(), 8*time.Millisecond)
+		expiringCtx, clean := context.WithTimeout(context.Background(), 45*time.Millisecond)
 		t.Cleanup(func() {
 			clean()
 		})
 
-		iter, duration, ok := WaitForWithContext(expiringCtx, alwaysFalse, 100*time.Millisecond, 3*time.Millisecond)
-		is.Equal(2, iter, "unexpected iteration count")
-		is.InEpsilon(10*time.Millisecond, duration, float64(500*time.Microsecond))
+		iter, duration, ok := WaitForWithContext(expiringCtx, alwaysFalse, 100*time.Millisecond, 30*time.Millisecond)
+		is.Equal(1, iter, "unexpected iteration count")
+		is.InDelta(45*time.Millisecond, duration, float64(10*time.Millisecond))
 		is.False(ok)
 	})
 
-	t.Run("canceled context stops everything", func(t *testing.T) {
-		t.Parallel()
+	t.Run("canceled context stops everything", func(t *testing.T) { //nolint:paralleltest
+		// t.Parallel()
 
-		testWithTimeout(t, testTimeout)
+		testWithTimeout(t, 200*time.Millisecond)
 		is := assert.New(t)
 
 		canceledCtx, cancel := context.WithCancel(context.Background())
 		cancel()
 
-		iter, duration, ok := WaitForWithContext(canceledCtx, alwaysFalse, 100*time.Millisecond, 1050*time.Microsecond)
+		iter, duration, ok := WaitForWithContext(canceledCtx, alwaysFalse, 100*time.Millisecond, 30*time.Millisecond)
 		is.Zero(iter, "unexpected iteration count")
-		is.InEpsilon(1*time.Millisecond, duration, float64(5*time.Microsecond))
+		is.InDelta(1*time.Millisecond, duration, float64(1*time.Millisecond))
 		is.False(ok)
 	})
 }
diff --git a/internal/xtime/README.md b/internal/xtime/README.md
new file mode 100644
index 0000000..73acd1e
--- /dev/null
+++ b/internal/xtime/README.md
@@ -0,0 +1,6 @@
+
+# xtime
+
+Lightweight mock for time package.
+
+A dedicated package such as [jonboulle/clockwork](https://github.com/jonboulle/clockwork/) would be better, but I would rather limit dependencies for this package. `clockwork` does not support Go 1.18 anymore.
diff --git a/internal/xtime/fake.go b/internal/xtime/fake.go
new file mode 100644
index 0000000..380e238
--- /dev/null
+++ b/internal/xtime/fake.go
@@ -0,0 +1,40 @@
+//nolint:revive
+package xtime
+
+import (
+	"time"
+)
+
+func NewFakeClock() *FakeClock {
+	return NewFakeClockAt(time.Now())
+}
+
+func NewFakeClockAt(t time.Time) *FakeClock {
+	return &FakeClock{
+		time: t,
+	}
+}
+
+type FakeClock struct {
+	_ noCopy
+
+	// Not protected by a mutex. If a warning is thrown in your tests,
+	// just disable parallel tests.
+	time time.Time
+}
+
+func (c *FakeClock) Now() time.Time {
+	return c.time
+}
+
+func (c *FakeClock) Since(t time.Time) time.Duration {
+	return c.time.Sub(t)
+}
+
+func (c *FakeClock) Until(t time.Time) time.Duration {
+	return t.Sub(c.time)
+}
+
+func (c *FakeClock) Sleep(d time.Duration) {
+	c.time = c.time.Add(d)
+}
diff --git a/internal/xtime/noCopy.go b/internal/xtime/noCopy.go
new file mode 100644
index 0000000..9d425ad
--- /dev/null
+++ b/internal/xtime/noCopy.go
@@ -0,0 +1,14 @@
+package xtime
+
+// noCopy may be added to structs which must not be copied
+// after the first use.
+//
+// See https://golang.org/issues/8005#issuecomment-190753527
+// for details.
+//
+// Note that it must not be embedded, due to the Lock and Unlock methods.
+type noCopy struct{}
+
+// Lock is a no-op used by -copylocks checker from `go vet`.
+func (*noCopy) Lock()   {}
+func (*noCopy) Unlock() {}
diff --git a/internal/xtime/real.go b/internal/xtime/real.go
new file mode 100644
index 0000000..df5a8db
--- /dev/null
+++ b/internal/xtime/real.go
@@ -0,0 +1,30 @@
+//nolint:revive
+package xtime
+
+import (
+	"time"
+)
+
+func NewRealClock() *RealClock {
+	return &RealClock{}
+}
+
+type RealClock struct {
+	_ noCopy
+}
+
+func (c *RealClock) Now() time.Time {
+	return time.Now()
+}
+
+func (c *RealClock) Since(t time.Time) time.Duration {
+	return time.Since(t)
+}
+
+func (c *RealClock) Until(t time.Time) time.Duration {
+	return time.Until(t)
+}
+
+func (c *RealClock) Sleep(d time.Duration) {
+	time.Sleep(d)
+}
diff --git a/internal/xtime/time.go b/internal/xtime/time.go
new file mode 100644
index 0000000..093a959
--- /dev/null
+++ b/internal/xtime/time.go
@@ -0,0 +1,33 @@
+//nolint:revive
+package xtime
+
+import "time"
+
+var clock Clock = &RealClock{}
+
+func SetClock(c Clock) {
+	clock = c
+}
+
+func Now() time.Time {
+	return clock.Now()
+}
+
+func Since(t time.Time) time.Duration {
+	return clock.Since(t)
+}
+
+func Until(t time.Time) time.Duration {
+	return clock.Until(t)
+}
+
+func Sleep(d time.Duration) {
+	clock.Sleep(d)
+}
+
+type Clock interface {
+	Now() time.Time
+	Since(t time.Time) time.Duration
+	Until(t time.Time) time.Duration
+	Sleep(d time.Duration)
+}
diff --git a/main_test.go b/main_test.go
index 911a9df..5595aee 100644
--- a/main_test.go
+++ b/main_test.go
@@ -3,9 +3,11 @@ package lo
 import (
 	"testing"
 
+	"github.com/samber/lo/internal/xtime"
 	"go.uber.org/goleak"
 )
 
 func TestMain(m *testing.M) {
+	xtime.SetClock(xtime.NewFakeClock())
 	goleak.VerifyTestMain(m)
 }
diff --git a/retry.go b/retry.go
index 0b7c979..e8b98c4 100644
--- a/retry.go
+++ b/retry.go
@@ -3,6 +3,8 @@ package lo
 import (
 	"sync"
 	"time"
+
+	"github.com/samber/lo/internal/xtime"
 )
 
 type debounce struct {
@@ -172,20 +174,20 @@ func Attempt(maxIteration int, f func(index int) error) (int, error) {
 func AttemptWithDelay(maxIteration int, delay time.Duration, f func(index int, duration time.Duration) error) (int, time.Duration, error) {
 	var err error
 
-	start := time.Now()
+	start := xtime.Now()
 
 	for i := 0; maxIteration <= 0 || i < maxIteration; i++ {
-		err = f(i, time.Since(start))
+		err = f(i, xtime.Since(start))
 		if err == nil {
-			return i + 1, time.Since(start), nil
+			return i + 1, xtime.Since(start), nil
 		}
 
 		if maxIteration <= 0 || i+1 < maxIteration {
-			time.Sleep(delay)
+			xtime.Sleep(delay)
 		}
 	}
 
-	return maxIteration, time.Since(start), err
+	return maxIteration, xtime.Since(start), err
 }
 
 // AttemptWhile invokes a function N times until it returns valid output.
@@ -224,23 +226,23 @@ func AttemptWhileWithDelay(maxIteration int, delay time.Duration, f func(int, ti
 	var err error
 	var shouldContinueInvoke bool
 
-	start := time.Now()
+	start := xtime.Now()
 
 	for i := 0; maxIteration <= 0 || i < maxIteration; i++ {
-		err, shouldContinueInvoke = f(i, time.Since(start))
+		err, shouldContinueInvoke = f(i, xtime.Since(start))
 		if !shouldContinueInvoke { // if shouldContinueInvoke is false, then return immediately
-			return i + 1, time.Since(start), err
+			return i + 1, xtime.Since(start), err
 		}
 		if err == nil {
-			return i + 1, time.Since(start), nil
+			return i + 1, xtime.Since(start), nil
 		}
 
 		if maxIteration <= 0 || i+1 < maxIteration {
-			time.Sleep(delay)
+			xtime.Sleep(delay)
 		}
 	}
 
-	return maxIteration, time.Since(start), err
+	return maxIteration, xtime.Since(start), err
 }
 
 type transactionStep[T any] struct {
diff --git a/retry_test.go b/retry_test.go
index 651ad4f..94cc27c 100644
--- a/retry_test.go
+++ b/retry_test.go
@@ -50,8 +50,8 @@ func TestAttempt(t *testing.T) {
 	is.NoError(err4)
 }
 
-func TestAttemptWithDelay(t *testing.T) {
-	t.Parallel()
+func TestAttemptWithDelay(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	is := assert.New(t)
 
 	err := errors.New("failed")
@@ -60,14 +60,14 @@ func TestAttemptWithDelay(t *testing.T) {
 		return nil
 	})
 	iter2, dur2, err2 := AttemptWithDelay(42, 10*time.Millisecond, func(i int, d time.Duration) error {
-		if i == 5 {
+		if i == 3 {
 			return nil
 		}
 
 		return err
 	})
 	iter3, dur3, err3 := AttemptWithDelay(2, 10*time.Millisecond, func(i int, d time.Duration) error {
-		if i == 5 {
+		if i == 3 {
 			return nil
 		}
 
@@ -82,20 +82,19 @@ func TestAttemptWithDelay(t *testing.T) {
 	})
 
 	is.Equal(1, iter1)
-	is.GreaterOrEqual(dur1, 0*time.Millisecond)
-	is.Less(dur1, 1*time.Millisecond)
+	is.InDelta(1*time.Microsecond, dur1, float64(1*time.Millisecond))
 	is.NoError(err1)
-	is.Equal(6, iter2)
-	is.Greater(dur2, 50*time.Millisecond)
-	is.Less(dur2, 60*time.Millisecond)
+
+	is.Equal(4, iter2)
+	is.InDelta(30*time.Millisecond, dur2, float64(5*time.Millisecond))
 	is.NoError(err2)
+
 	is.Equal(2, iter3)
-	is.Greater(dur3, 10*time.Millisecond)
-	is.Less(dur3, 20*time.Millisecond)
+	is.InDelta(10*time.Millisecond, dur3, float64(5*time.Millisecond))
 	is.ErrorIs(err3, err)
+
 	is.Equal(11, iter4)
-	is.Greater(dur4, 100*time.Millisecond)
-	is.Less(dur4, 115*time.Millisecond)
+	is.InDelta(100*time.Millisecond, dur4, float64(5*time.Millisecond))
 	is.NoError(err4)
 }
 
@@ -178,8 +177,8 @@ func TestAttemptWhile(t *testing.T) {
 	is.NoError(err7)
 }
 
-func TestAttemptWhileWithDelay(t *testing.T) {
-	t.Parallel()
+func TestAttemptWhileWithDelay(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	is := assert.New(t)
 
 	err := errors.New("failed")
@@ -189,21 +188,19 @@ func TestAttemptWhileWithDelay(t *testing.T) {
 	})
 
 	is.Equal(1, iter1)
-	is.GreaterOrEqual(dur1, 0*time.Millisecond)
-	is.Less(dur1, 1*time.Millisecond)
+	is.InDelta(1*time.Microsecond, dur1, float64(3*time.Millisecond))
 	is.NoError(err1)
 
 	iter2, dur2, err2 := AttemptWhileWithDelay(42, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
-		if i == 5 {
+		if i == 3 {
 			return nil, true
 		}
 
 		return err, true
 	})
 
-	is.Equal(6, iter2)
-	is.Greater(dur2, 50*time.Millisecond)
-	is.Less(dur2, 60*time.Millisecond)
+	is.Equal(4, iter2)
+	is.InDelta(30*time.Millisecond, dur2, float64(5*time.Millisecond))
 	is.NoError(err2)
 
 	iter3, dur3, err3 := AttemptWhileWithDelay(2, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
@@ -215,8 +212,7 @@ func TestAttemptWhileWithDelay(t *testing.T) {
 	})
 
 	is.Equal(2, iter3)
-	is.Greater(dur3, 10*time.Millisecond)
-	is.Less(dur3, 20*time.Millisecond)
+	is.InDelta(10*time.Millisecond, dur3, float64(5*time.Millisecond))
 	is.ErrorIs(err3, err)
 
 	iter4, dur4, err4 := AttemptWhileWithDelay(0, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
@@ -228,21 +224,19 @@ func TestAttemptWhileWithDelay(t *testing.T) {
 	})
 
 	is.Equal(11, iter4)
-	is.Greater(dur4, 100*time.Millisecond)
-	is.Less(dur4, 115*time.Millisecond)
+	is.InDelta(100*time.Millisecond, dur4, float64(5*time.Millisecond))
 	is.NoError(err4)
 
 	iter5, dur5, err5 := AttemptWhileWithDelay(0, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
-		if i == 5 {
+		if i == 3 {
 			return nil, false
 		}
 
 		return err, true
 	})
 
-	is.Equal(6, iter5)
-	is.Greater(dur5, 10*time.Millisecond)
-	is.Less(dur5, 115*time.Millisecond)
+	is.Equal(4, iter5)
+	is.InDelta(30*time.Millisecond, dur5, float64(5*time.Millisecond))
 	is.NoError(err5)
 
 	iter6, dur6, err6 := AttemptWhileWithDelay(0, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
@@ -250,8 +244,7 @@ func TestAttemptWhileWithDelay(t *testing.T) {
 	})
 
 	is.Equal(1, iter6)
-	is.Less(dur6, 10*time.Millisecond)
-	is.Less(dur6, 115*time.Millisecond)
+	is.InDelta(1*time.Microsecond, dur6, float64(5*time.Millisecond))
 	is.NoError(err6)
 
 	iter7, dur7, err7 := AttemptWhileWithDelay(42, 10*time.Millisecond, func(i int, d time.Duration) (error, bool) {
@@ -266,12 +259,12 @@ func TestAttemptWhileWithDelay(t *testing.T) {
 	})
 
 	is.Equal(42, iter7)
-	is.Less(dur7, 500*time.Millisecond)
+	is.InDelta(410*time.Millisecond, dur7, float64(5*time.Millisecond))
 	is.NoError(err7)
 }
 
-func TestDebounce(t *testing.T) {
-	t.Parallel()
+func TestDebounce(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 
 	f1 := func() {
 		println("1. Called once after 10ms when func stopped invoking!")
@@ -283,43 +276,43 @@ func TestDebounce(t *testing.T) {
 		println("3. Called once after 10ms when func stopped invoking!")
 	}
 
-	d1, _ := NewDebounce(10*time.Millisecond, f1)
+	d1, _ := NewDebounce(100*time.Millisecond, f1)
 
 	// execute 3 times
 	for i := 0; i < 3; i++ {
 		for j := 0; j < 10; j++ {
 			d1()
 		}
-		time.Sleep(20 * time.Millisecond)
+		time.Sleep(200 * time.Millisecond)
 	}
 
-	d2, _ := NewDebounce(10*time.Millisecond, f2)
+	d2, _ := NewDebounce(100*time.Millisecond, f2)
 
 	// execute once because it is always invoked and only last invoke is worked after 100ms
 	for i := 0; i < 3; i++ {
 		for j := 0; j < 5; j++ {
 			d2()
 		}
-		time.Sleep(5 * time.Millisecond)
+		time.Sleep(50 * time.Millisecond)
 	}
 
-	time.Sleep(10 * time.Millisecond)
+	time.Sleep(100 * time.Millisecond)
 
 	// execute once because it is canceled after 200ms.
-	d3, cancel := NewDebounce(10*time.Millisecond, f3)
+	d3, cancel := NewDebounce(100*time.Millisecond, f3)
 	for i := 0; i < 3; i++ {
 		for j := 0; j < 10; j++ {
 			d3()
 		}
-		time.Sleep(20 * time.Millisecond)
+		time.Sleep(200 * time.Millisecond)
 		if i == 0 {
 			cancel()
 		}
 	}
 }
 
-func TestDebounceBy(t *testing.T) {
-	t.Parallel()
+func TestDebounceBy(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	is := assert.New(t)
 
 	mu := sync.Mutex{}
@@ -344,7 +337,7 @@ func TestDebounceBy(t *testing.T) {
 		// fmt.Printf("[key=%d] 3. Called once after 10ms when func stopped invoking!\n", key)
 	}
 
-	d1, _ := NewDebounceBy(10*time.Millisecond, f1)
+	d1, _ := NewDebounceBy(100*time.Millisecond, f1)
 
 	// execute 3 times
 	for i := 0; i < 3; i++ {
@@ -353,16 +346,19 @@ func TestDebounceBy(t *testing.T) {
 				d1(k)
 			}
 		}
-		time.Sleep(20 * time.Millisecond)
+		time.Sleep(200 * time.Millisecond)
 	}
 
+	// Wait for debounced calls to complete
+	time.Sleep(150 * time.Millisecond)
+
 	mu.Lock()
 	is.Equal(30, output[0])
 	is.Equal(30, output[1])
 	is.Equal(30, output[2])
 	mu.Unlock()
 
-	d2, _ := NewDebounceBy(10*time.Millisecond, f2)
+	d2, _ := NewDebounceBy(100*time.Millisecond, f2)
 
 	// execute once because it is always invoked and only last invoke is worked after 100ms
 	for i := 0; i < 3; i++ {
@@ -371,10 +367,11 @@ func TestDebounceBy(t *testing.T) {
 				d2(k)
 			}
 		}
-		time.Sleep(5 * time.Millisecond)
+		time.Sleep(50 * time.Millisecond)
 	}
 
-	time.Sleep(10 * time.Millisecond)
+	// Wait for debounced calls to complete
+	time.Sleep(150 * time.Millisecond)
 
 	mu.Lock()
 	is.Equal(45, output[0])
@@ -383,7 +380,7 @@ func TestDebounceBy(t *testing.T) {
 	mu.Unlock()
 
 	// execute once because it is canceled after 200ms.
-	d3, cancel := NewDebounceBy(10*time.Millisecond, f3)
+	d3, cancel := NewDebounceBy(100*time.Millisecond, f3)
 	for i := 0; i < 3; i++ {
 		for j := 0; j < 10; j++ {
 			for k := 0; k < 3; k++ {
@@ -391,7 +388,7 @@ func TestDebounceBy(t *testing.T) {
 			}
 		}
 
-		time.Sleep(20 * time.Millisecond)
+		time.Sleep(200 * time.Millisecond)
 		if i == 0 {
 			for k := 0; k < 3; k++ {
 				cancel(k)
@@ -399,6 +396,9 @@ func TestDebounceBy(t *testing.T) {
 		}
 	}
 
+	// Wait for debounced calls to complete
+	time.Sleep(150 * time.Millisecond)
+
 	mu.Lock()
 	is.Equal(75, output[0])
 	is.Equal(75, output[1])
@@ -502,14 +502,14 @@ func TestTransaction(t *testing.T) {
 	}
 }
 
-func TestNewThrottle(t *testing.T) {
-	t.Parallel()
+func TestNewThrottle(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	is := assert.New(t)
 	callCount := 0
 	f1 := func() {
 		callCount++
 	}
-	th, reset := NewThrottle(10*time.Millisecond, f1)
+	th, reset := NewThrottle(100*time.Millisecond, f1)
 
 	is.Zero(callCount)
 	for j := 0; j < 100; j++ {
@@ -517,7 +517,7 @@ func TestNewThrottle(t *testing.T) {
 	}
 	is.Equal(1, callCount)
 
-	time.Sleep(15 * time.Millisecond)
+	time.Sleep(150 * time.Millisecond)
 
 	for j := 0; j < 100; j++ {
 		th()
@@ -531,14 +531,14 @@ func TestNewThrottle(t *testing.T) {
 	is.Equal(3, callCount)
 }
 
-func TestNewThrottleWithCount(t *testing.T) {
-	t.Parallel()
+func TestNewThrottleWithCount(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	is := assert.New(t)
 	callCount := 0
 	f1 := func() {
 		callCount++
 	}
-	th, reset := NewThrottleWithCount(10*time.Millisecond, 3, f1)
+	th, reset := NewThrottleWithCount(100*time.Millisecond, 3, f1)
 
 	// the function does not throttle for initial count number
 	for i := 0; i < 20; i++ {
@@ -546,7 +546,7 @@ func TestNewThrottleWithCount(t *testing.T) {
 	}
 	is.Equal(3, callCount)
 
-	time.Sleep(15 * time.Millisecond)
+	time.Sleep(150 * time.Millisecond)
 
 	for i := 0; i < 20; i++ {
 		th()
@@ -562,8 +562,8 @@ func TestNewThrottleWithCount(t *testing.T) {
 	is.Equal(9, callCount)
 }
 
-func TestNewThrottleBy(t *testing.T) {
-	t.Parallel()
+func TestNewThrottleBy(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	is := assert.New(t)
 	callCountA := 0
 	callCountB := 0
@@ -574,7 +574,7 @@ func TestNewThrottleBy(t *testing.T) {
 			callCountB++
 		}
 	}
-	th, reset := NewThrottleBy(10*time.Millisecond, f1)
+	th, reset := NewThrottleBy(100*time.Millisecond, f1)
 
 	is.Zero(callCountA)
 	is.Zero(callCountB)
@@ -585,7 +585,7 @@ func TestNewThrottleBy(t *testing.T) {
 	is.Equal(1, callCountA)
 	is.Equal(1, callCountB)
 
-	time.Sleep(15 * time.Millisecond)
+	time.Sleep(150 * time.Millisecond)
 
 	for j := 0; j < 100; j++ {
 		th("a")
@@ -602,8 +602,8 @@ func TestNewThrottleBy(t *testing.T) {
 	is.Equal(2, callCountB)
 }
 
-func TestNewThrottleByWithCount(t *testing.T) {
-	t.Parallel()
+func TestNewThrottleByWithCount(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	is := assert.New(t)
 
 	callCountA := 0
@@ -615,7 +615,7 @@ func TestNewThrottleByWithCount(t *testing.T) {
 			callCountB++
 		}
 	}
-	th, reset := NewThrottleByWithCount(10*time.Millisecond, 3, f1)
+	th, reset := NewThrottleByWithCount(100*time.Millisecond, 3, f1)
 
 	// the function does not throttle for initial count number
 	for i := 0; i < 20; i++ {
@@ -625,7 +625,7 @@ func TestNewThrottleByWithCount(t *testing.T) {
 	is.Equal(3, callCountA)
 	is.Equal(3, callCountB)
 
-	time.Sleep(15 * time.Millisecond)
+	time.Sleep(150 * time.Millisecond)
 
 	for i := 0; i < 20; i++ {
 		th("a")
diff --git a/time.go b/time.go
index 1e3b827..f295adb 100644
--- a/time.go
+++ b/time.go
@@ -1,6 +1,8 @@
 package lo
 
-import "time"
+import (
+	"time"
+)
 
 // Duration returns the time taken to execute a function.
 // Play: https://go.dev/play/p/HQfbBbAXaFP
diff --git a/time_test.go b/time_test.go
index 3764fc7..c8a74ff 100644
--- a/time_test.go
+++ b/time_test.go
@@ -7,47 +7,52 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestDuration(t *testing.T) {
-	t.Parallel()
+func TestDuration(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	is := assert.New(t)
+	testWithTimeout(t, 200*time.Millisecond)
 
-	result := Duration(func() { time.Sleep(10 * time.Millisecond) })
-	is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+	result := Duration(func() { time.Sleep(100 * time.Millisecond) })
+	is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 }
 
-func TestDurationX(t *testing.T) {
-	t.Parallel()
+func TestDurationX(t *testing.T) { //nolint:paralleltest
+	// t.Parallel()
 	is := assert.New(t)
+	testWithTimeout(t, 1500*time.Millisecond)
 
 	{
-		result := Duration0(func() { time.Sleep(10 * time.Millisecond) })
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		result := Duration0(func() { time.Sleep(100 * time.Millisecond) })
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 	}
 
 	{
-		a, result := Duration1(func() string { time.Sleep(10 * time.Millisecond); return "a" })
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		a, result := Duration1(func() string { time.Sleep(100 * time.Millisecond); return "a" })
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 		is.Equal("a", a)
 	}
 
 	{
-		a, b, result := Duration2(func() (string, string) { time.Sleep(10 * time.Millisecond); return "a", "b" })
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		a, b, result := Duration2(func() (string, string) { time.Sleep(100 * time.Millisecond); return "a", "b" })
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 		is.Equal("a", a)
 		is.Equal("b", b)
 	}
 
 	{
-		a, b, c, result := Duration3(func() (string, string, string) { time.Sleep(10 * time.Millisecond); return "a", "b", "c" })
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		a, b, c, result := Duration3(func() (string, string, string) { time.Sleep(100 * time.Millisecond); return "a", "b", "c" })
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 		is.Equal("a", a)
 		is.Equal("b", b)
 		is.Equal("c", c)
 	}
 
 	{
-		a, b, c, d, result := Duration4(func() (string, string, string, string) { time.Sleep(10 * time.Millisecond); return "a", "b", "c", "d" })
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		a, b, c, d, result := Duration4(func() (string, string, string, string) {
+			time.Sleep(100 * time.Millisecond)
+			return "a", "b", "c", "d"
+		})
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 		is.Equal("a", a)
 		is.Equal("b", b)
 		is.Equal("c", c)
@@ -56,10 +61,10 @@ func TestDurationX(t *testing.T) {
 
 	{
 		a, b, c, d, e, result := Duration5(func() (string, string, string, string, string) {
-			time.Sleep(10 * time.Millisecond)
+			time.Sleep(100 * time.Millisecond)
 			return "a", "b", "c", "d", "e"
 		})
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 		is.Equal("a", a)
 		is.Equal("b", b)
 		is.Equal("c", c)
@@ -69,10 +74,10 @@ func TestDurationX(t *testing.T) {
 
 	{
 		a, b, c, d, e, f, result := Duration6(func() (string, string, string, string, string, string) {
-			time.Sleep(10 * time.Millisecond)
+			time.Sleep(100 * time.Millisecond)
 			return "a", "b", "c", "d", "e", "f"
 		})
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 		is.Equal("a", a)
 		is.Equal("b", b)
 		is.Equal("c", c)
@@ -83,10 +88,10 @@ func TestDurationX(t *testing.T) {
 
 	{
 		a, b, c, d, e, f, g, result := Duration7(func() (string, string, string, string, string, string, string) {
-			time.Sleep(10 * time.Millisecond)
+			time.Sleep(100 * time.Millisecond)
 			return "a", "b", "c", "d", "e", "f", "g"
 		})
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 		is.Equal("a", a)
 		is.Equal("b", b)
 		is.Equal("c", c)
@@ -98,10 +103,10 @@ func TestDurationX(t *testing.T) {
 
 	{
 		a, b, c, d, e, f, g, h, result := Duration8(func() (string, string, string, string, string, string, string, string) {
-			time.Sleep(10 * time.Millisecond)
+			time.Sleep(100 * time.Millisecond)
 			return "a", "b", "c", "d", "e", "f", "g", "h"
 		})
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 		is.Equal("a", a)
 		is.Equal("b", b)
 		is.Equal("c", c)
@@ -114,10 +119,10 @@ func TestDurationX(t *testing.T) {
 
 	{
 		a, b, c, d, e, f, g, h, i, result := Duration9(func() (string, string, string, string, string, string, string, string, string) {
-			time.Sleep(10 * time.Millisecond)
+			time.Sleep(100 * time.Millisecond)
 			return "a", "b", "c", "d", "e", "f", "g", "h", "i"
 		})
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 		is.Equal("a", a)
 		is.Equal("b", b)
 		is.Equal("c", c)
@@ -131,10 +136,10 @@ func TestDurationX(t *testing.T) {
 
 	{
 		a, b, c, d, e, f, g, h, i, j, result := Duration10(func() (string, string, string, string, string, string, string, string, string, string) {
-			time.Sleep(10 * time.Millisecond)
+			time.Sleep(100 * time.Millisecond)
 			return "a", "b", "c", "d", "e", "f", "g", "h", "i", "j"
 		})
-		is.InEpsilon(10*time.Millisecond, result, float64(2*time.Millisecond))
+		is.InDelta(100*time.Millisecond, result, float64(20*time.Millisecond))
 		is.Equal("a", a)
 		is.Equal("b", b)
 		is.Equal("c", c)