diff --git a/internal/base/base.go b/internal/base/base.go
index 6123dd1..997e1d2 100644
--- a/internal/base/base.go
+++ b/internal/base/base.go
@@ -7,6 +7,8 @@ package base
 
 import (
 	"context"
+	"crypto/md5"
+	"encoding/hex"
 	"fmt"
 	"sync"
 	"time"
@@ -170,9 +172,12 @@ func SchedulerHistoryKey(entryID string) string {
 }
 
 // UniqueKey returns a redis key with the given type, payload, and queue name.
-// FIXME: We probably need to generate a hash of payload to make this key unique
 func UniqueKey(qname, tasktype string, payload []byte) string {
-	return fmt.Sprintf("%sunique:%s:%s", QueueKeyPrefix(qname), tasktype, string(payload))
+	if payload == nil {
+		return fmt.Sprintf("%sunique:%s:", QueueKeyPrefix(qname), tasktype)
+	}
+	checksum := md5.Sum(payload)
+	return fmt.Sprintf("%sunique:%s:%s", QueueKeyPrefix(qname), tasktype, hex.EncodeToString(checksum[:]))
 }
 
 // TaskMessage is the internal representation of a task with additional metadata fields.
diff --git a/internal/base/base_test.go b/internal/base/base_test.go
index ebd15ce..9df725e 100644
--- a/internal/base/base_test.go
+++ b/internal/base/base_test.go
@@ -6,6 +6,8 @@ package base
 
 import (
 	"context"
+	"crypto/md5"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"sync"
@@ -276,6 +278,19 @@ func toBytes(m map[string]interface{}) []byte {
 }
 
 func TestUniqueKey(t *testing.T) {
+	payload1 := toBytes(map[string]interface{}{"a": 123, "b": "hello", "c": true})
+	payload2 := toBytes(map[string]interface{}{"b": "hello", "c": true, "a": 123})
+	payload3 := toBytes(map[string]interface{}{
+		"address": map[string]string{"line": "123 Main St", "city": "Boston", "state": "MA"},
+		"names":   []string{"bob", "mike", "rob"}})
+	payload4 := toBytes(map[string]interface{}{
+		"time":     time.Date(2020, time.July, 28, 0, 0, 0, 0, time.UTC),
+		"duration": time.Hour})
+
+	checksum := func(data []byte) string {
+		sum := md5.Sum(data)
+		return hex.EncodeToString(sum[:])
+	}
 	tests := []struct {
 		desc     string
 		qname    string
@@ -287,41 +302,29 @@ func TestUniqueKey(t *testing.T) {
 			"with primitive types",
 			"default",
 			"email:send",
-			toBytes(map[string]interface{}{"a": 123, "b": "hello", "c": true}),
-			fmt.Sprintf("asynq:{default}:unique:email:send:%s",
-				string(toBytes(map[string]interface{}{"a": 123, "b": "hello", "c": true}))),
+			payload1,
+			fmt.Sprintf("asynq:{default}:unique:email:send:%s", checksum(payload1)),
 		},
 		{
 			"with unsorted keys",
 			"default",
 			"email:send",
-			toBytes(map[string]interface{}{"b": "hello", "c": true, "a": 123}),
-			fmt.Sprintf("asynq:{default}:unique:email:send:%s",
-				string(toBytes(map[string]interface{}{"b": "hello", "c": true, "a": 123}))),
+			payload2,
+			fmt.Sprintf("asynq:{default}:unique:email:send:%s", checksum(payload2)),
 		},
 		{
 			"with composite types",
 			"default",
 			"email:send",
-			toBytes(map[string]interface{}{
-				"address": map[string]string{"line": "123 Main St", "city": "Boston", "state": "MA"},
-				"names":   []string{"bob", "mike", "rob"}}),
-			fmt.Sprintf("asynq:{default}:unique:email:send:%s",
-				string(toBytes(map[string]interface{}{
-					"address": map[string]string{"line": "123 Main St", "city": "Boston", "state": "MA"},
-					"names":   []string{"bob", "mike", "rob"}}))),
+			payload3,
+			fmt.Sprintf("asynq:{default}:unique:email:send:%s", checksum(payload3)),
 		},
 		{
 			"with complex types",
 			"default",
 			"email:send",
-			toBytes(map[string]interface{}{
-				"time":     time.Date(2020, time.July, 28, 0, 0, 0, 0, time.UTC),
-				"duration": time.Hour}),
-			fmt.Sprintf("asynq:{default}:unique:email:send:%s",
-				string(toBytes(map[string]interface{}{
-					"time":     time.Date(2020, time.July, 28, 0, 0, 0, 0, time.UTC),
-					"duration": time.Hour}))),
+			payload4,
+			fmt.Sprintf("asynq:{default}:unique:email:send:%s", checksum(payload4)),
 		},
 		{
 			"with nil payload",