diff --git a/README.md b/README.md
index 28dbc85..ec9791c 100644
--- a/README.md
+++ b/README.md
@@ -72,9 +72,8 @@ func main() {
     bg := asynq.NewBackground(r, &asynq.Config{
         // Specify how many concurrent workers to use
         Concurrency: 10,
-        // You can optionally create multiple queues
-        // with different priority level
-        Queues: map[string]uint{
+        // You can optionally create multiple queues with different priority.
+        Queues: map[string]int{
             "critical": 6,
             "default":  3,
             "low":      1,
diff --git a/background.go b/background.go
index e878cbc..fa533a2 100644
--- a/background.go
+++ b/background.go
@@ -47,7 +47,7 @@ type Background struct {
 type Config struct {
 	// Maximum number of concurrent processing of tasks.
 	//
-	// If set to zero or negative value, NewBackground will overwrite the value to one.
+	// If set to a zero or negative value, NewBackground will overwrite the value to one.
 	Concurrency int
 
 	// Function to calculate retry delay for a failed task.
@@ -59,15 +59,15 @@ type Config struct {
 	// t is the task in question.
 	RetryDelayFunc func(n int, e error, t *Task) time.Duration
 
-	// List of queues to process with given priority level. Keys are the names of the
-	// queues and values are associated priority level.
+	// List of queues to process with given priority value. Keys are the names of the
+	// queues and values are associated priority value.
 	//
 	// If set to nil or not specified, the background will process only the "default" queue.
 	//
 	// Priority is treated as follows to avoid starving low priority queues.
 	//
 	// Example:
-	// Queues: map[string]uint{
+	// Queues: map[string]int{
 	//     "critical": 6,
 	//     "default":  3,
 	//     "low":      1,
@@ -75,7 +75,9 @@ type Config struct {
 	// With the above config and given that all queues are not empty, the tasks
 	// in "critical", "default", "low" should be processed 60%, 30%, 10% of
 	// the time respectively.
-	Queues map[string]uint
+	//
+	// If a queue has a zero or negative priority value, the queue will be ignored.
+	Queues map[string]int
 
 	// StrictPriority indicates whether the queue priority should be treated strictly.
 	//
@@ -92,7 +94,7 @@ func defaultDelayFunc(n int, e error, t *Task) time.Duration {
 	return time.Duration(s) * time.Second
 }
 
-var defaultQueueConfig = map[string]uint{
+var defaultQueueConfig = map[string]int{
 	base.DefaultQueueName: 1,
 }
 
@@ -107,8 +109,13 @@ func NewBackground(r RedisConnOpt, cfg *Config) *Background {
 	if delayFunc == nil {
 		delayFunc = defaultDelayFunc
 	}
-	queues := cfg.Queues
-	if queues == nil || len(queues) == 0 {
+	queues := make(map[string]int)
+	for qname, p := range cfg.Queues {
+		if p > 0 {
+			queues[qname] = p
+		}
+	}
+	if len(queues) == 0 {
 		queues = defaultQueueConfig
 	}
 
diff --git a/background_test.go b/background_test.go
index 0b6f5ec..32aaeb2 100644
--- a/background_test.go
+++ b/background_test.go
@@ -43,16 +43,16 @@ func TestBackground(t *testing.T) {
 
 func TestGCD(t *testing.T) {
 	tests := []struct {
-		input []uint
-		want  uint
+		input []int
+		want  int
 	}{
-		{[]uint{6, 2, 12}, 2},
-		{[]uint{3, 3, 3}, 3},
-		{[]uint{6, 3, 1}, 1},
-		{[]uint{1}, 1},
-		{[]uint{1, 0, 2}, 1},
-		{[]uint{8, 0, 4}, 4},
-		{[]uint{9, 12, 18, 30}, 3},
+		{[]int{6, 2, 12}, 2},
+		{[]int{3, 3, 3}, 3},
+		{[]int{6, 3, 1}, 1},
+		{[]int{1}, 1},
+		{[]int{1, 0, 2}, 1},
+		{[]int{8, 0, 4}, 4},
+		{[]int{9, 12, 18, 30}, 3},
 	}
 
 	for _, tc := range tests {
@@ -65,46 +65,46 @@ func TestGCD(t *testing.T) {
 
 func TestNormalizeQueueCfg(t *testing.T) {
 	tests := []struct {
-		input map[string]uint
-		want  map[string]uint
+		input map[string]int
+		want  map[string]int
 	}{
 		{
-			input: map[string]uint{
+			input: map[string]int{
 				"high":    100,
 				"default": 20,
 				"low":     5,
 			},
-			want: map[string]uint{
+			want: map[string]int{
 				"high":    20,
 				"default": 4,
 				"low":     1,
 			},
 		},
 		{
-			input: map[string]uint{
+			input: map[string]int{
 				"default": 10,
 			},
-			want: map[string]uint{
+			want: map[string]int{
 				"default": 1,
 			},
 		},
 		{
-			input: map[string]uint{
+			input: map[string]int{
 				"critical": 5,
 				"default":  1,
 			},
-			want: map[string]uint{
+			want: map[string]int{
 				"critical": 5,
 				"default":  1,
 			},
 		},
 		{
-			input: map[string]uint{
+			input: map[string]int{
 				"critical": 6,
 				"default":  3,
 				"low":      0,
 			},
-			want: map[string]uint{
+			want: map[string]int{
 				"critical": 2,
 				"default":  1,
 				"low":      0,
diff --git a/benchmark_test.go b/benchmark_test.go
index eb5fa22..5988adb 100644
--- a/benchmark_test.go
+++ b/benchmark_test.go
@@ -120,7 +120,7 @@ func BenchmarkEndToEndMultipleQueues(b *testing.B) {
 		client := NewClient(redis)
 		bg := NewBackground(redis, &Config{
 			Concurrency: 10,
-			Queues: map[string]uint{
+			Queues: map[string]int{
 				"high":    6,
 				"default": 3,
 				"low":     1,
diff --git a/heartbeat_test.go b/heartbeat_test.go
index d4fffb2..268ea76 100644
--- a/heartbeat_test.go
+++ b/heartbeat_test.go
@@ -23,10 +23,10 @@ func TestHeartbeater(t *testing.T) {
 		interval    time.Duration
 		host        string
 		pid         int
-		queues      map[string]uint
+		queues      map[string]int
 		concurrency int
 	}{
-		{time.Second, "some.address.ec2.aws.com", 45678, map[string]uint{"default": 1}, 10},
+		{time.Second, "some.address.ec2.aws.com", 45678, map[string]int{"default": 1}, 10},
 	}
 
 	timeCmpOpt := cmpopts.EquateApproxTime(10 * time.Millisecond)
diff --git a/internal/base/base.go b/internal/base/base.go
index b7896fa..12f01df 100644
--- a/internal/base/base.go
+++ b/internal/base/base.go
@@ -91,7 +91,7 @@ type TaskMessage struct {
 type ProcessInfo struct {
 	mu                sync.Mutex
 	Concurrency       int
-	Queues            map[string]uint
+	Queues            map[string]int
 	StrictPriority    bool
 	PID               int
 	Host              string
@@ -101,7 +101,7 @@ type ProcessInfo struct {
 }
 
 // NewProcessInfo returns a new instance of ProcessInfo.
-func NewProcessInfo(host string, pid, concurrency int, queues map[string]uint, strict bool) *ProcessInfo {
+func NewProcessInfo(host string, pid, concurrency int, queues map[string]int, strict bool) *ProcessInfo {
 	return &ProcessInfo{
 		Host:           host,
 		PID:            pid,
diff --git a/internal/base/base_test.go b/internal/base/base_test.go
index 00be893..46050c0 100644
--- a/internal/base/base_test.go
+++ b/internal/base/base_test.go
@@ -82,7 +82,7 @@ func TestProcessInfoKey(t *testing.T) {
 
 // Note: Run this test with -race flag to check for data race.
 func TestProcessInfoSetter(t *testing.T) {
-	pi := NewProcessInfo("localhost", 1234, 8, map[string]uint{"default": 1}, false)
+	pi := NewProcessInfo("localhost", 1234, 8, map[string]int{"default": 1}, false)
 
 	var wg sync.WaitGroup
 
diff --git a/internal/rdb/inspect.go b/internal/rdb/inspect.go
index 578b636..d0f4be7 100644
--- a/internal/rdb/inspect.go
+++ b/internal/rdb/inspect.go
@@ -245,10 +245,10 @@ func reverse(x []string) {
 // for the list operation.
 type Pagination struct {
 	// Number of items in the page.
-	Size uint
+	Size int
 
 	// Page number starting from zero.
-	Page uint
+	Page int
 }
 
 func (p Pagination) start() int64 {
diff --git a/internal/rdb/inspect_test.go b/internal/rdb/inspect_test.go
index 91422c0..cd671c2 100644
--- a/internal/rdb/inspect_test.go
+++ b/internal/rdb/inspect_test.go
@@ -317,8 +317,8 @@ func TestListEnqueuedPagination(t *testing.T) {
 	tests := []struct {
 		desc      string
 		qname     string
-		page      uint
-		size      uint
+		page      int
+		size      int
 		wantSize  int
 		wantFirst string
 		wantLast  string
@@ -418,8 +418,8 @@ func TestListInProgressPagination(t *testing.T) {
 
 	tests := []struct {
 		desc      string
-		page      uint
-		size      uint
+		page      int
+		size      int
 		wantSize  int
 		wantFirst string
 		wantLast  string
@@ -524,8 +524,8 @@ func TestListScheduledPagination(t *testing.T) {
 
 	tests := []struct {
 		desc      string
-		page      uint
-		size      uint
+		page      int
+		size      int
 		wantSize  int
 		wantFirst string
 		wantLast  string
@@ -667,8 +667,8 @@ func TestListRetryPagination(t *testing.T) {
 
 	tests := []struct {
 		desc      string
-		page      uint
-		size      uint
+		page      int
+		size      int
 		wantSize  int
 		wantFirst string
 		wantLast  string
@@ -800,8 +800,8 @@ func TestListDeadPagination(t *testing.T) {
 
 	tests := []struct {
 		desc      string
-		page      uint
-		size      uint
+		page      int
+		size      int
 		wantSize  int
 		wantFirst string
 		wantLast  string
@@ -2056,7 +2056,7 @@ func TestListProcesses(t *testing.T) {
 
 	ps1 := &base.ProcessInfo{
 		Concurrency:       10,
-		Queues:            map[string]uint{"default": 1},
+		Queues:            map[string]int{"default": 1},
 		Host:              "do.droplet1",
 		PID:               1234,
 		State:             "running",
@@ -2066,7 +2066,7 @@ func TestListProcesses(t *testing.T) {
 
 	ps2 := &base.ProcessInfo{
 		Concurrency:       20,
-		Queues:            map[string]uint{"email": 1},
+		Queues:            map[string]int{"email": 1},
 		Host:              "do.droplet2",
 		PID:               9876,
 		State:             "stopped",
diff --git a/internal/rdb/rdb_test.go b/internal/rdb/rdb_test.go
index 8b8d52e..accc52d 100644
--- a/internal/rdb/rdb_test.go
+++ b/internal/rdb/rdb_test.go
@@ -745,7 +745,7 @@ func TestReadWriteClearProcessInfo(t *testing.T) {
 	r := setup(t)
 	pinfo := &base.ProcessInfo{
 		Concurrency:       10,
-		Queues:            map[string]uint{"default": 2, "email": 5, "low": 1},
+		Queues:            map[string]int{"default": 2, "email": 5, "low": 1},
 		PID:               98765,
 		Host:              "localhost",
 		State:             "running",
diff --git a/processor.go b/processor.go
index b91c4ca..6bc4b1c 100644
--- a/processor.go
+++ b/processor.go
@@ -24,7 +24,7 @@ type processor struct {
 
 	handler Handler
 
-	queueConfig map[string]uint
+	queueConfig map[string]int
 
 	// orderedQueues is set only in strict-priority mode.
 	orderedQueues []string
@@ -324,7 +324,7 @@ func uniq(names []string, l int) []string {
 
 // sortByPriority returns a list of queue names sorted by
 // their priority level in descending order.
-func sortByPriority(qcfg map[string]uint) []string {
+func sortByPriority(qcfg map[string]int) []string {
 	var queues []*queue
 	for qname, n := range qcfg {
 		queues = append(queues, &queue{qname, n})
@@ -339,7 +339,7 @@ func sortByPriority(qcfg map[string]uint) []string {
 
 type queue struct {
 	name     string
-	priority uint
+	priority int
 }
 
 type byPriority []*queue
@@ -350,21 +350,21 @@ func (x byPriority) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
 
 // normalizeQueueCfg divides priority numbers by their
 // greatest common divisor.
-func normalizeQueueCfg(queueCfg map[string]uint) map[string]uint {
-	var xs []uint
+func normalizeQueueCfg(queueCfg map[string]int) map[string]int {
+	var xs []int
 	for _, x := range queueCfg {
 		xs = append(xs, x)
 	}
 	d := gcd(xs...)
-	res := make(map[string]uint)
+	res := make(map[string]int)
 	for q, x := range queueCfg {
 		res[q] = x / d
 	}
 	return res
 }
 
-func gcd(xs ...uint) uint {
-	fn := func(x, y uint) uint {
+func gcd(xs ...int) int {
+	fn := func(x, y int) int {
 		for y > 0 {
 			x, y = y, x%y
 		}
diff --git a/processor_test.go b/processor_test.go
index 1bc5d99..079bf6e 100644
--- a/processor_test.go
+++ b/processor_test.go
@@ -192,11 +192,11 @@ func TestProcessorQueues(t *testing.T) {
 	})
 
 	tests := []struct {
-		queueCfg map[string]uint
+		queueCfg map[string]int
 		want     []string
 	}{
 		{
-			queueCfg: map[string]uint{
+			queueCfg: map[string]int{
 				"high":    6,
 				"default": 3,
 				"low":     1,
@@ -204,7 +204,7 @@ func TestProcessorQueues(t *testing.T) {
 			want: []string{"high", "default", "low"},
 		},
 		{
-			queueCfg: map[string]uint{
+			queueCfg: map[string]int{
 				"default": 1,
 			},
 			want: []string{"default"},
@@ -274,7 +274,7 @@ func TestProcessorWithStrictPriority(t *testing.T) {
 			processed = append(processed, task)
 			return nil
 		}
-		queueCfg := map[string]uint{
+		queueCfg := map[string]int{
 			"critical":            3,
 			base.DefaultQueueName: 2,
 			"low":                 1,
diff --git a/scheduler.go b/scheduler.go
index 8c59ebe..7276f4c 100644
--- a/scheduler.go
+++ b/scheduler.go
@@ -23,7 +23,7 @@ type scheduler struct {
 	qnames []string
 }
 
-func newScheduler(r *rdb.RDB, avgInterval time.Duration, qcfg map[string]uint) *scheduler {
+func newScheduler(r *rdb.RDB, avgInterval time.Duration, qcfg map[string]int) *scheduler {
 	var qnames []string
 	for q := range qcfg {
 		qnames = append(qnames, q)
diff --git a/tools/asynqmon/cmd/ls.go b/tools/asynqmon/cmd/ls.go
index a4b85ee..3bec832 100644
--- a/tools/asynqmon/cmd/ls.go
+++ b/tools/asynqmon/cmd/ls.go
@@ -44,16 +44,24 @@ asynqmon ls enqueued:critical -> List tasks from critical queue
 }
 
 // Flags
-var pageSize uint
-var pageNum uint
+var pageSize int
+var pageNum int
 
 func init() {
 	rootCmd.AddCommand(lsCmd)
-	lsCmd.Flags().UintVar(&pageSize, "size", 30, "page size")
-	lsCmd.Flags().UintVar(&pageNum, "page", 0, "page number - zero indexed (default 0)")
+	lsCmd.Flags().IntVar(&pageSize, "size", 30, "page size")
+	lsCmd.Flags().IntVar(&pageNum, "page", 0, "page number - zero indexed (default 0)")
 }
 
 func ls(cmd *cobra.Command, args []string) {
+	if pageSize < 0 {
+		fmt.Println("page size cannot be negative.")
+		os.Exit(1)
+	}
+	if pageNum < 0 {
+		fmt.Println("page number cannot be negative.")
+		os.Exit(1)
+	}
 	c := redis.NewClient(&redis.Options{
 		Addr:     viper.GetString("uri"),
 		DB:       viper.GetInt("db"),
diff --git a/tools/asynqmon/cmd/ps.go b/tools/asynqmon/cmd/ps.go
index ef25876..7761886 100644
--- a/tools/asynqmon/cmd/ps.go
+++ b/tools/asynqmon/cmd/ps.go
@@ -87,11 +87,11 @@ func timeAgo(since time.Time) string {
 	return fmt.Sprintf("%v ago", d)
 }
 
-func formatQueues(qmap map[string]uint) string {
+func formatQueues(qmap map[string]int) string {
 	// sort queues by priority and name
 	type queue struct {
 		name     string
-		priority uint
+		priority int
 	}
 	var queues []*queue
 	for qname, p := range qmap {