diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 89c6549b..0c517a52 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -29,7 +29,7 @@ uname -sp && tmux -V && echo $TERM
 
 Also include:
 
-- Your platform (Linux, OS X, or whatever).
+- Your platform (Linux, macOS, or whatever).
 
 - A brief description of the problem with steps to reproduce.
 
diff --git a/.github/README.md b/.github/README.md
index 5590d0b2..353f10ec 100644
--- a/.github/README.md
+++ b/.github/README.md
@@ -4,7 +4,7 @@ tmux is a terminal multiplexer: it enables a number of terminals to be created,
 accessed, and controlled from a single screen. tmux may be detached from a
 screen and continue running in the background, then later reattached.
 
-This release runs on OpenBSD, FreeBSD, NetBSD, Linux, OS X and Solaris.
+This release runs on OpenBSD, FreeBSD, NetBSD, Linux, macOS and Solaris.
 
 ## Dependencies
 
diff --git a/README b/README
index 8732a027..57329629 100644
--- a/README
+++ b/README
@@ -4,7 +4,7 @@ tmux is a terminal multiplexer: it enables a number of terminals to be created,
 accessed, and controlled from a single screen. tmux may be detached from a
 screen and continue running in the background, then later reattached.
 
-This release runs on OpenBSD, FreeBSD, NetBSD, Linux, OS X and Solaris.
+This release runs on OpenBSD, FreeBSD, NetBSD, Linux, macOS and Solaris.
 
 * Dependencies
 
diff --git a/README.ja b/README.ja
index 1580df52..3c944738 100644
--- a/README.ja
+++ b/README.ja
@@ -3,7 +3,7 @@ tmuxへようこそ!
 tmuxはターミナルマルチプレクサーです。複数のターミナルを一つのスクリーン内に作成し、操作することができます。
 バックグラウンドで処理を実行中に一度スクリーンから離れて後から復帰することも可能です。
 
-OpenBSD、FreeBSD、NetBSD、Linux、OS X、Solarisで実行できます。
+OpenBSD、FreeBSD、NetBSD、Linux、macOS、Solarisで実行できます。
 
 tmuxはlibevent 2.x.に依存します。 下記からダウンロードしてください。