diff --git a/asynq.go b/asynq.go
index 23a3d93..b9da48d 100644
--- a/asynq.go
+++ b/asynq.go
@@ -1,8 +1,12 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 /*
 TODOs:
-- [P0] Go docs + License comment
+- [P0] Go docs
 */
 
 // Task represents a task to be performed.
diff --git a/asynq_test.go b/asynq_test.go
index 3f96d1c..8e16090 100644
--- a/asynq_test.go
+++ b/asynq_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/background.go b/background.go
index 316f527..572718b 100644
--- a/background.go
+++ b/background.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/background_test.go b/background_test.go
index 5b648ca..36b26e4 100644
--- a/background_test.go
+++ b/background_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/benchmark_test.go b/benchmark_test.go
index 00c4a6a..b90ee46 100644
--- a/benchmark_test.go
+++ b/benchmark_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/client.go b/client.go
index ac6afd8..92c03ce 100644
--- a/client.go
+++ b/client.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/client_test.go b/client_test.go
index 0f6b04d..158652c 100644
--- a/client_test.go
+++ b/client_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/doc.go b/doc.go
index 7e08e11..8d2ab89 100644
--- a/doc.go
+++ b/doc.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 /*
 Package asynq provides a framework for background task processing.
 
diff --git a/internal/asynqtest/asynqtest.go b/internal/asynqtest/asynqtest.go
index f3791d2..3a39c68 100644
--- a/internal/asynqtest/asynqtest.go
+++ b/internal/asynqtest/asynqtest.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 // Package asynqtest defines test helpers for asynq and its internal packages.
 package asynqtest
 
diff --git a/internal/base/base.go b/internal/base/base.go
index 00a5a17..b1862c8 100644
--- a/internal/base/base.go
+++ b/internal/base/base.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 // Package base defines foundational types and constants used in asynq package.
 package base
 
diff --git a/internal/base/base_test.go b/internal/base/base_test.go
index 2f375cc..a48f10e 100644
--- a/internal/base/base_test.go
+++ b/internal/base/base_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package base
 
 import (
diff --git a/internal/rdb/benchmark_test.go b/internal/rdb/benchmark_test.go
index 1bbd333..930d740 100644
--- a/internal/rdb/benchmark_test.go
+++ b/internal/rdb/benchmark_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package rdb
 
 import (
diff --git a/internal/rdb/inspect.go b/internal/rdb/inspect.go
index 3cb9071..44cec56 100644
--- a/internal/rdb/inspect.go
+++ b/internal/rdb/inspect.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package rdb
 
 import (
diff --git a/internal/rdb/inspect_test.go b/internal/rdb/inspect_test.go
index 2111244..8738708 100644
--- a/internal/rdb/inspect_test.go
+++ b/internal/rdb/inspect_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package rdb
 
 import (
diff --git a/internal/rdb/rdb.go b/internal/rdb/rdb.go
index cd6b0a7..8b41053 100644
--- a/internal/rdb/rdb.go
+++ b/internal/rdb/rdb.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 // Package rdb encapsulates the interactions with redis.
 package rdb
 
diff --git a/internal/rdb/rdb_test.go b/internal/rdb/rdb_test.go
index c4d8c31..126d8c9 100644
--- a/internal/rdb/rdb_test.go
+++ b/internal/rdb/rdb_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package rdb
 
 import (
diff --git a/payload.go b/payload.go
index 8430abc..15a29bf 100644
--- a/payload.go
+++ b/payload.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/payload_test.go b/payload_test.go
index 095608f..2631844 100644
--- a/payload_test.go
+++ b/payload_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/processor.go b/processor.go
index 39d82b3..b45f756 100644
--- a/processor.go
+++ b/processor.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/processor_test.go b/processor_test.go
index b23daae..5063bd5 100644
--- a/processor_test.go
+++ b/processor_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/scheduler.go b/scheduler.go
index c88d862..36d4cbf 100644
--- a/scheduler.go
+++ b/scheduler.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/scheduler_test.go b/scheduler_test.go
index aaffeb0..387466d 100644
--- a/scheduler_test.go
+++ b/scheduler_test.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package asynq
 
 import (
diff --git a/tools/asynqmon/cmd/del.go b/tools/asynqmon/cmd/del.go
index c70f3c1..a85a9b0 100644
--- a/tools/asynqmon/cmd/del.go
+++ b/tools/asynqmon/cmd/del.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package cmd
 
 import (
diff --git a/tools/asynqmon/cmd/delall.go b/tools/asynqmon/cmd/delall.go
index 5211167..860e8cd 100644
--- a/tools/asynqmon/cmd/delall.go
+++ b/tools/asynqmon/cmd/delall.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package cmd
 
 import (
diff --git a/tools/asynqmon/cmd/enq.go b/tools/asynqmon/cmd/enq.go
index 6096f40..2bcd137 100644
--- a/tools/asynqmon/cmd/enq.go
+++ b/tools/asynqmon/cmd/enq.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package cmd
 
 import (
diff --git a/tools/asynqmon/cmd/enqall.go b/tools/asynqmon/cmd/enqall.go
index d60bef4..90586f0 100644
--- a/tools/asynqmon/cmd/enqall.go
+++ b/tools/asynqmon/cmd/enqall.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package cmd
 
 import (
diff --git a/tools/asynqmon/cmd/kill.go b/tools/asynqmon/cmd/kill.go
index eb3f1d0..7289048 100644
--- a/tools/asynqmon/cmd/kill.go
+++ b/tools/asynqmon/cmd/kill.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package cmd
 
 import (
diff --git a/tools/asynqmon/cmd/killall.go b/tools/asynqmon/cmd/killall.go
index e981893..7865b59 100644
--- a/tools/asynqmon/cmd/killall.go
+++ b/tools/asynqmon/cmd/killall.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package cmd
 
 import (
diff --git a/tools/asynqmon/cmd/ls.go b/tools/asynqmon/cmd/ls.go
index 4dc223f..009bbff 100644
--- a/tools/asynqmon/cmd/ls.go
+++ b/tools/asynqmon/cmd/ls.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package cmd
 
 import (
diff --git a/tools/asynqmon/cmd/root.go b/tools/asynqmon/cmd/root.go
index c3ce463..9846c7d 100644
--- a/tools/asynqmon/cmd/root.go
+++ b/tools/asynqmon/cmd/root.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package cmd
 
 import (
diff --git a/tools/asynqmon/cmd/stats.go b/tools/asynqmon/cmd/stats.go
index f3e4a1f..5826364 100644
--- a/tools/asynqmon/cmd/stats.go
+++ b/tools/asynqmon/cmd/stats.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package cmd
 
 import (
diff --git a/tools/asynqmon/main.go b/tools/asynqmon/main.go
index a4b0919..7575710 100644
--- a/tools/asynqmon/main.go
+++ b/tools/asynqmon/main.go
@@ -1,3 +1,7 @@
+// Copyright 2020 Kentaro Hibino. All rights reserved.
+// Use of this source code is governed by a MIT license
+// that can be found in the LICENSE file.
+
 package main
 
 import "github.com/hibiken/asynq/tools/asynqmon/cmd"