diff --git a/rdb.go b/rdb.go
index 4dcb107..bd22df0 100644
--- a/rdb.go
+++ b/rdb.go
@@ -21,11 +21,7 @@ const (
 	inProgress   = "asynq:in_progress"     // SET
 )
 
-var (
-	errDequeueTimeout  = errors.New("blocking dequeue operation timed out")
-	errSerializeTask   = errors.New("could not encode task message into json")
-	errDeserializeTask = errors.New("could not decode task message from json")
-)
+var errDequeueTimeout = errors.New("blocking dequeue operation timed out")
 
 // rdb encapsulates the interactions with redis server.
 type rdb struct {
@@ -46,7 +42,7 @@ func newRDB(opt *RedisOpt) *rdb {
 func (r *rdb) enqueue(msg *taskMessage) error {
 	bytes, err := json.Marshal(msg)
 	if err != nil {
-		return fmt.Errorf("could not encode task into JSON: %v", err)
+		return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
 	}
 	qname := queuePrefix + msg.Queue
 	pipe := r.client.Pipeline()
@@ -54,8 +50,7 @@ func (r *rdb) enqueue(msg *taskMessage) error {
 	pipe.LPush(qname, string(bytes))
 	_, err = pipe.Exec()
 	if err != nil {
-		return fmt.Errorf("could not enqueue task %+v to %q: %v",
-			msg, qname, err)
+		return fmt.Errorf("could not enqueue the task %+v to %q: %v", msg, qname, err)
 	}
 	return nil
 }
@@ -69,12 +64,12 @@ func (r *rdb) dequeue(qname string, timeout time.Duration) (*taskMessage, error)
 		return nil, errDequeueTimeout
 	}
 	if err != nil {
-		return nil, fmt.Errorf("command BRPOPLPUSH %q %q %v failed: %v", qname, inProgress, timeout, err)
+		return nil, fmt.Errorf("command `BRPOPLPUSH %q %q %v` failed: %v", qname, inProgress, timeout, err)
 	}
 	var msg taskMessage
 	err = json.Unmarshal([]byte(data), &msg)
 	if err != nil {
-		return nil, errDeserializeTask
+		return nil, fmt.Errorf("could not unmarshal %v to json: %v", data, err)
 	}
 	fmt.Printf("[DEBUG] perform task %+v from %s\n", msg, qname)
 	return &msg, nil
@@ -83,12 +78,12 @@ func (r *rdb) dequeue(qname string, timeout time.Duration) (*taskMessage, error)
 func (r *rdb) lrem(key string, msg *taskMessage) error {
 	bytes, err := json.Marshal(msg)
 	if err != nil {
-		return fmt.Errorf("could not encode task into JSON: %v", err)
+		return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
 	}
 	// NOTE: count ZERO means "remove all elements equal to val"
 	err = r.client.LRem(key, 0, string(bytes)).Err()
 	if err != nil {
-		return fmt.Errorf("command LREM %s 0 %s failed: %v", key, string(bytes), err)
+		return fmt.Errorf("command `LREM %s 0 %s` failed: %v", key, string(bytes), err)
 	}
 	return nil
 }
@@ -97,13 +92,12 @@ func (r *rdb) lrem(key string, msg *taskMessage) error {
 func (r *rdb) schedule(zset string, processAt time.Time, msg *taskMessage) error {
 	bytes, err := json.Marshal(msg)
 	if err != nil {
-		return fmt.Errorf("could not encode task into JSON: %v", err)
+		return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
 	}
 	score := float64(processAt.Unix())
 	err = r.client.ZAdd(zset, &redis.Z{Member: string(bytes), Score: score}).Err()
 	if err != nil {
-		return fmt.Errorf("command ZADD %s %.1f %s failed: %v",
-			zset, score, string(bytes), err)
+		return fmt.Errorf("command `ZADD %s %.1f %s` failed: %v", zset, score, string(bytes), err)
 	}
 	return nil
 }
@@ -116,7 +110,7 @@ const deadExpirationInDays = 90
 func (r *rdb) kill(msg *taskMessage) error {
 	bytes, err := json.Marshal(msg)
 	if err != nil {
-		return fmt.Errorf("could not encode task into JSON: %v", err)
+		return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
 	}
 	now := time.Now()
 	pipe := r.client.Pipeline()