diff --git a/asynq.go b/asynq.go
index c3cc28e..febf174 100644
--- a/asynq.go
+++ b/asynq.go
@@ -16,7 +16,7 @@ type Task struct {
 	// Type indicates the kind of the task to be performed.
 	Type string
 
-	// Payload holds data needed for the task execution.
+	// Payload holds data needed to process the task.
 	Payload Payload
 }
 
diff --git a/internal/base/base.go b/internal/base/base.go
index 5339976..00a5a17 100644
--- a/internal/base/base.go
+++ b/internal/base/base.go
@@ -32,23 +32,26 @@ func FailureKey(t time.Time) string {
 }
 
 // TaskMessage is the internal representation of a task with additional metadata fields.
-// Serialized data of this type gets written in redis.
+// Serialized data of this type gets written to redis.
 type TaskMessage struct {
-	//-------- Task fields --------
-	// Type represents the kind of task.
+	// Type indicates the kind of the task to be performed.
 	Type string
+
 	// Payload holds data needed to process the task.
 	Payload map[string]interface{}
 
-	//-------- Metadata fields --------
-	// ID is a unique identifier for each task
+	// ID is a unique identifier for each task.
 	ID xid.ID
-	// Queue is a name this message should be enqueued to
+
+	// Queue is a name this message should be enqueued to.
 	Queue string
+
 	// Retry is the max number of retry for this task.
 	Retry int
-	// Retried is the number of times we've retried this task so far
+
+	// Retried is the number of times we've retried this task so far.
 	Retried int
-	// ErrorMsg holds the error message from the last failure
+
+	// ErrorMsg holds the error message from the last failure.
 	ErrorMsg string
 }
diff --git a/internal/rdb/rdb.go b/internal/rdb/rdb.go
index b466cbe..300e402 100644
--- a/internal/rdb/rdb.go
+++ b/internal/rdb/rdb.go
@@ -36,38 +36,32 @@ func (r *RDB) Close() error {
 	return r.client.Close()
 }
 
-// Enqueue inserts the given task to the end of the queue.
-// It also adds the queue name to the "all-queues" list.
+// Enqueue inserts the given task to the tail of the queue.
 func (r *RDB) Enqueue(msg *base.TaskMessage) error {
 	bytes, err := json.Marshal(msg)
 	if err != nil {
-		return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
+		return err
 	}
 	qname := base.QueuePrefix + msg.Queue
-	pipe := r.client.Pipeline()
-	pipe.LPush(qname, string(bytes))
-	_, err = pipe.Exec()
-	if err != nil {
-		return fmt.Errorf("could not enqueue the task %+v to %q: %v", msg, qname, err)
-	}
-	return nil
+	return r.client.LPush(qname, string(bytes)).Err()
 }
 
 // Dequeue blocks until there is a task available to be processed,
-// once a task is available, it adds the task to "in progress" list
-// and returns the task.
+// once a task is available, it adds the task to "in progress" queue
+// and returns the task. If there are no tasks for the entire timeout
+// duration, it returns ErrDequeueTimeout.
 func (r *RDB) Dequeue(timeout time.Duration) (*base.TaskMessage, error) {
 	data, err := r.client.BRPopLPush(base.DefaultQueue, base.InProgressQueue, timeout).Result()
 	if err == redis.Nil {
 		return nil, ErrDequeueTimeout
 	}
 	if err != nil {
-		return nil, fmt.Errorf("command `BRPOPLPUSH %q %q %v` failed: %v", base.DefaultQueue, base.InProgressQueue, timeout, err)
+		return nil, err
 	}
 	var msg base.TaskMessage
 	err = json.Unmarshal([]byte(data), &msg)
 	if err != nil {
-		return nil, fmt.Errorf("could not unmarshal %v to json: %v", data, err)
+		return nil, err
 	}
 	return &msg, nil
 }
@@ -76,7 +70,7 @@ func (r *RDB) Dequeue(timeout time.Duration) (*base.TaskMessage, error) {
 func (r *RDB) Done(msg *base.TaskMessage) error {
 	bytes, err := json.Marshal(msg)
 	if err != nil {
-		return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
+		return err
 	}
 	// Note: LREM count ZERO means "remove all elements equal to val"
 	// KEYS[1] -> asynq:in_progress
@@ -94,10 +88,9 @@ func (r *RDB) Done(msg *base.TaskMessage) error {
 	now := time.Now()
 	processedKey := base.ProcessedKey(now)
 	expireAt := now.Add(statsTTL)
-	_, err = script.Run(r.client,
+	return script.Run(r.client,
 		[]string{base.InProgressQueue, processedKey},
-		string(bytes), expireAt.Unix()).Result()
-	return err
+		string(bytes), expireAt.Unix()).Err()
 }
 
 // Requeue moves the task from in-progress queue to the default
@@ -105,7 +98,7 @@ func (r *RDB) Done(msg *base.TaskMessage) error {
 func (r *RDB) Requeue(msg *base.TaskMessage) error {
 	bytes, err := json.Marshal(msg)
 	if err != nil {
-		return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
+		return err
 	}
 	// Note: Use RPUSH to push to the head of the queue.
 	// KEYS[1] -> asynq:in_progress
@@ -116,22 +109,20 @@ func (r *RDB) Requeue(msg *base.TaskMessage) error {
 	redis.call("RPUSH", KEYS[2], ARGV[1])
 	return redis.status_reply("OK")
 	`)
-	_, err = script.Run(r.client, []string{base.InProgressQueue, base.DefaultQueue}, string(bytes)).Result()
-	return err
+	return script.Run(r.client,
+		[]string{base.InProgressQueue, base.DefaultQueue},
+		string(bytes)).Err()
 }
 
 // Schedule adds the task to the backlog queue to be processed in the future.
 func (r *RDB) Schedule(msg *base.TaskMessage, processAt time.Time) error {
 	bytes, err := json.Marshal(msg)
 	if err != nil {
-		return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
+		return err
 	}
 	score := float64(processAt.Unix())
-	err = r.client.ZAdd(base.ScheduledQueue, &redis.Z{Member: string(bytes), Score: score}).Err()
-	if err != nil {
-		return fmt.Errorf("command `ZADD %s %.1f %s` failed: %v", base.ScheduledQueue, score, string(bytes), err)
-	}
-	return nil
+	return r.client.ZAdd(base.ScheduledQueue,
+		&redis.Z{Member: string(bytes), Score: score}).Err()
 }
 
 // Retry moves the task from in-progress to retry queue, incrementing retry count
diff --git a/internal/rdb/rdb_test.go b/internal/rdb/rdb_test.go
index d072a0a..026dc93 100644
--- a/internal/rdb/rdb_test.go
+++ b/internal/rdb/rdb_test.go
@@ -42,13 +42,23 @@ func TestDequeue(t *testing.T) {
 	r := setup(t)
 	t1 := newTaskMessage("send_email", map[string]interface{}{"subject": "hello!"})
 	tests := []struct {
-		enqueued   []*base.TaskMessage
-		want       *base.TaskMessage
-		err        error
-		inProgress int64 // length of "in-progress" tasks after dequeue
+		enqueued       []*base.TaskMessage
+		want           *base.TaskMessage
+		err            error
+		wantInProgress []*base.TaskMessage
 	}{
-		{enqueued: []*base.TaskMessage{t1}, want: t1, err: nil, inProgress: 1},
-		{enqueued: []*base.TaskMessage{}, want: nil, err: ErrDequeueTimeout, inProgress: 0},
+		{
+			enqueued:       []*base.TaskMessage{t1},
+			want:           t1,
+			err:            nil,
+			wantInProgress: []*base.TaskMessage{t1},
+		},
+		{
+			enqueued:       []*base.TaskMessage{},
+			want:           nil,
+			err:            ErrDequeueTimeout,
+			wantInProgress: []*base.TaskMessage{},
+		},
 	}
 
 	for _, tc := range tests {
@@ -61,8 +71,11 @@ func TestDequeue(t *testing.T) {
 				got, err, tc.want, tc.err)
 			continue
 		}
-		if l := r.client.LLen(base.InProgressQueue).Val(); l != tc.inProgress {
-			t.Errorf("%q has length %d, want %d", base.InProgressQueue, l, tc.inProgress)
+
+		gotInProgressRaw := r.client.LRange(base.InProgressQueue, 0, -1).Val()
+		gotInProgress := mustUnmarshalSlice(t, gotInProgressRaw)
+		if diff := cmp.Diff(tc.wantInProgress, gotInProgress, sortMsgOpt); diff != "" {
+			t.Errorf("mismatch found in %q: (-want,+got):\n%s", base.InProgressQueue, diff)
 		}
 	}
 }
@@ -82,11 +95,6 @@ func TestDone(t *testing.T) {
 			target:         t1,
 			wantInProgress: []*base.TaskMessage{t2},
 		},
-		{
-			inProgress:     []*base.TaskMessage{t2},
-			target:         t1,
-			wantInProgress: []*base.TaskMessage{t2},
-		},
 		{
 			inProgress:     []*base.TaskMessage{t1},
 			target:         t1,
@@ -107,7 +115,7 @@ func TestDone(t *testing.T) {
 		data := r.client.LRange(base.InProgressQueue, 0, -1).Val()
 		gotInProgress := mustUnmarshalSlice(t, data)
 		if diff := cmp.Diff(tc.wantInProgress, gotInProgress, sortMsgOpt); diff != "" {
-			t.Errorf("mismatch found in %q after calling (*RDB).Done: (-want, +got):\n%s", base.InProgressQueue, diff)
+			t.Errorf("mismatch found in %q: (-want, +got):\n%s", base.InProgressQueue, diff)
 			continue
 		}
 
@@ -177,6 +185,132 @@ func TestRequeue(t *testing.T) {
 	}
 }
 
+func TestSchedule(t *testing.T) {
+	r := setup(t)
+	t1 := newTaskMessage("send_email", map[string]interface{}{"subject": "hello"})
+	tests := []struct {
+		msg       *base.TaskMessage
+		processAt time.Time
+	}{
+		{t1, time.Now().Add(15 * time.Minute)},
+	}
+
+	for _, tc := range tests {
+		flushDB(t, r) // clean up db before each test case
+
+		desc := fmt.Sprintf("(*RDB).Schedule(%v, %v)", tc.msg, tc.processAt)
+		err := r.Schedule(tc.msg, tc.processAt)
+		if err != nil {
+			t.Errorf("%s = %v, want nil", desc, err)
+			continue
+		}
+
+		res := r.client.ZRangeWithScores(base.ScheduledQueue, 0, -1).Val()
+		if len(res) != 1 {
+			t.Errorf("%s inserted %d items to %q, want 1 items inserted", desc, len(res), base.ScheduledQueue)
+			continue
+		}
+		if res[0].Score != float64(tc.processAt.Unix()) {
+			t.Errorf("%s inserted an item with score %f, want %f", desc, res[0].Score, float64(tc.processAt.Unix()))
+			continue
+		}
+	}
+}
+
+func TestRetry(t *testing.T) {
+	r := setup(t)
+	t1 := newTaskMessage("send_email", map[string]interface{}{"subject": "Hola!"})
+	t2 := newTaskMessage("gen_thumbnail", map[string]interface{}{"path": "some/path/to/image.jpg"})
+	t3 := newTaskMessage("reindex", nil)
+	t1.Retried = 10
+	errMsg := "SMTP server is not responding"
+	t1AfterRetry := &base.TaskMessage{
+		ID:       t1.ID,
+		Type:     t1.Type,
+		Payload:  t1.Payload,
+		Queue:    t1.Queue,
+		Retry:    t1.Retry,
+		Retried:  t1.Retried + 1,
+		ErrorMsg: errMsg,
+	}
+	now := time.Now()
+
+	tests := []struct {
+		inProgress     []*base.TaskMessage
+		retry          []sortedSetEntry
+		msg            *base.TaskMessage
+		processAt      time.Time
+		errMsg         string
+		wantInProgress []*base.TaskMessage
+		wantRetry      []sortedSetEntry
+	}{
+		{
+			inProgress: []*base.TaskMessage{t1, t2},
+			retry: []sortedSetEntry{
+				{t3, now.Add(time.Minute).Unix()},
+			},
+			msg:            t1,
+			processAt:      now.Add(5 * time.Minute),
+			errMsg:         errMsg,
+			wantInProgress: []*base.TaskMessage{t2},
+			wantRetry: []sortedSetEntry{
+				{t1AfterRetry, now.Add(5 * time.Minute).Unix()},
+				{t3, now.Add(time.Minute).Unix()},
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		flushDB(t, r)
+		seedInProgressQueue(t, r, tc.inProgress)
+		seedRetryQueue(t, r, tc.retry)
+
+		err := r.Retry(tc.msg, tc.processAt, tc.errMsg)
+		if err != nil {
+			t.Errorf("(*RDB).Retry = %v, want nil", err)
+			continue
+		}
+
+		gotInProgressRaw := r.client.LRange(base.InProgressQueue, 0, -1).Val()
+		gotInProgress := mustUnmarshalSlice(t, gotInProgressRaw)
+		if diff := cmp.Diff(tc.wantInProgress, gotInProgress, sortMsgOpt); diff != "" {
+			t.Errorf("mismatch found in %q; (-want, +got)\n%s", base.InProgressQueue, diff)
+		}
+
+		gotRetryRaw := r.client.ZRangeWithScores(base.RetryQueue, 0, -1).Val()
+		var gotRetry []sortedSetEntry
+		for _, z := range gotRetryRaw {
+			gotRetry = append(gotRetry, sortedSetEntry{
+				Msg:   mustUnmarshal(t, z.Member.(string)),
+				Score: int64(z.Score),
+			})
+		}
+		cmpOpt := cmp.AllowUnexported(sortedSetEntry{})
+		if diff := cmp.Diff(tc.wantRetry, gotRetry, cmpOpt, sortZSetEntryOpt); diff != "" {
+			t.Errorf("mismatch found in %q; (-want, +got)\n%s", base.RetryQueue, diff)
+		}
+
+		processedKey := base.ProcessedKey(time.Now())
+		gotProcessed := r.client.Get(processedKey).Val()
+		if gotProcessed != "1" {
+			t.Errorf("GET %q = %q, want 1", processedKey, gotProcessed)
+		}
+		gotTTL := r.client.TTL(processedKey).Val()
+		if gotTTL > statsTTL {
+			t.Errorf("TTL %q = %v, want less than or equal to %v", processedKey, gotTTL, statsTTL)
+		}
+
+		failureKey := base.FailureKey(time.Now())
+		gotFailure := r.client.Get(failureKey).Val()
+		if gotFailure != "1" {
+			t.Errorf("GET %q = %q, want 1", failureKey, gotFailure)
+		}
+		gotTTL = r.client.TTL(processedKey).Val()
+		if gotTTL > statsTTL {
+			t.Errorf("TTL %q = %v, want less than or equal to %v", failureKey, gotTTL, statsTTL)
+		}
+	}
+}
 func TestKill(t *testing.T) {
 	r := setup(t)
 	t1 := newTaskMessage("send_email", nil)
@@ -412,132 +546,3 @@ func TestCheckAndEnqueue(t *testing.T) {
 		}
 	}
 }
-
-func TestSchedule(t *testing.T) {
-	r := setup(t)
-	tests := []struct {
-		msg       *base.TaskMessage
-		processAt time.Time
-	}{
-		{
-			newTaskMessage("send_email", map[string]interface{}{"subject": "hello"}),
-			time.Now().Add(15 * time.Minute),
-		},
-	}
-
-	for _, tc := range tests {
-		flushDB(t, r) // clean up db before each test case
-
-		desc := fmt.Sprintf("(*RDB).Schedule(%v, %v)", tc.msg, tc.processAt)
-		err := r.Schedule(tc.msg, tc.processAt)
-		if err != nil {
-			t.Errorf("%s = %v, want nil", desc, err)
-			continue
-		}
-
-		res := r.client.ZRangeWithScores(base.ScheduledQueue, 0, -1).Val()
-		if len(res) != 1 {
-			t.Errorf("%s inserted %d items to %q, want 1 items inserted", desc, len(res), base.ScheduledQueue)
-			continue
-		}
-		if res[0].Score != float64(tc.processAt.Unix()) {
-			t.Errorf("%s inserted an item with score %f, want %f", desc, res[0].Score, float64(tc.processAt.Unix()))
-			continue
-		}
-	}
-}
-
-func TestRetry(t *testing.T) {
-	r := setup(t)
-	t1 := newTaskMessage("send_email", map[string]interface{}{"subject": "Hola!"})
-	t2 := newTaskMessage("gen_thumbnail", map[string]interface{}{"path": "some/path/to/image.jpg"})
-	t3 := newTaskMessage("reindex", nil)
-	t1.Retried = 10
-	errMsg := "SMTP server is not responding"
-	t1AfterRetry := &base.TaskMessage{
-		ID:       t1.ID,
-		Type:     t1.Type,
-		Payload:  t1.Payload,
-		Queue:    t1.Queue,
-		Retry:    t1.Retry,
-		Retried:  t1.Retried + 1,
-		ErrorMsg: errMsg,
-	}
-	now := time.Now()
-
-	tests := []struct {
-		inProgress     []*base.TaskMessage
-		retry          []sortedSetEntry
-		msg            *base.TaskMessage
-		processAt      time.Time
-		errMsg         string
-		wantInProgress []*base.TaskMessage
-		wantRetry      []sortedSetEntry
-	}{
-		{
-			inProgress: []*base.TaskMessage{t1, t2},
-			retry: []sortedSetEntry{
-				{t3, now.Add(time.Minute).Unix()},
-			},
-			msg:            t1,
-			processAt:      now.Add(5 * time.Minute),
-			errMsg:         errMsg,
-			wantInProgress: []*base.TaskMessage{t2},
-			wantRetry: []sortedSetEntry{
-				{t1AfterRetry, now.Add(5 * time.Minute).Unix()},
-				{t3, now.Add(time.Minute).Unix()},
-			},
-		},
-	}
-
-	for _, tc := range tests {
-		flushDB(t, r)
-		seedInProgressQueue(t, r, tc.inProgress)
-		seedRetryQueue(t, r, tc.retry)
-
-		err := r.Retry(tc.msg, tc.processAt, tc.errMsg)
-		if err != nil {
-			t.Errorf("(*RDB).Retry = %v, want nil", err)
-			continue
-		}
-
-		gotInProgressRaw := r.client.LRange(base.InProgressQueue, 0, -1).Val()
-		gotInProgress := mustUnmarshalSlice(t, gotInProgressRaw)
-		if diff := cmp.Diff(tc.wantInProgress, gotInProgress, sortMsgOpt); diff != "" {
-			t.Errorf("mismatch found in %q; (-want, +got)\n%s", base.InProgressQueue, diff)
-		}
-
-		gotRetryRaw := r.client.ZRangeWithScores(base.RetryQueue, 0, -1).Val()
-		var gotRetry []sortedSetEntry
-		for _, z := range gotRetryRaw {
-			gotRetry = append(gotRetry, sortedSetEntry{
-				Msg:   mustUnmarshal(t, z.Member.(string)),
-				Score: int64(z.Score),
-			})
-		}
-		cmpOpt := cmp.AllowUnexported(sortedSetEntry{})
-		if diff := cmp.Diff(tc.wantRetry, gotRetry, cmpOpt, sortZSetEntryOpt); diff != "" {
-			t.Errorf("mismatch found in %q; (-want, +got)\n%s", base.RetryQueue, diff)
-		}
-
-		processedKey := base.ProcessedKey(time.Now())
-		gotProcessed := r.client.Get(processedKey).Val()
-		if gotProcessed != "1" {
-			t.Errorf("GET %q = %q, want 1", processedKey, gotProcessed)
-		}
-		gotTTL := r.client.TTL(processedKey).Val()
-		if gotTTL > statsTTL {
-			t.Errorf("TTL %q = %v, want less than or equal to %v", processedKey, gotTTL, statsTTL)
-		}
-
-		failureKey := base.FailureKey(time.Now())
-		gotFailure := r.client.Get(failureKey).Val()
-		if gotFailure != "1" {
-			t.Errorf("GET %q = %q, want 1", failureKey, gotFailure)
-		}
-		gotTTL = r.client.TTL(processedKey).Val()
-		if gotTTL > statsTTL {
-			t.Errorf("TTL %q = %v, want less than or equal to %v", failureKey, gotTTL, statsTTL)
-		}
-	}
-}