diff --git a/chapter/macos.tex b/chapter/macos.tex
index f6bb130..724abe4 100644
--- a/chapter/macos.tex
+++ b/chapter/macos.tex
@@ -30,6 +30,15 @@ \section{安装 Homebrew}
   source ~/.zshrc
 \end{lstlisting}
 
+\subsection{Xcode}
+
+根据 \href{https://docs.brew.sh/Xcode\#supported-xcode-versions}{Homebrew 网站}的提示\footnote{原文是 Homebrew supports and recommends the latest Xcode and/or Command Line Tools available for your platform},
+推荐用户在安装 Homebrew 前先安装 Xcode.
+在\textsf{终端} 执行以下命令即可:
+\begin{lstlisting}[language=bash]
+  xcode-select --install
+\end{lstlisting}
+
 \section{安装 Mac\TeX}
 
 Mac\TeX{} 是 \TeX{} Live 在 macOS 下的再打包版本, 额外加入了一些辅助程序. 如果已经安装了 Homebrew,
diff --git a/chapter/windows.tex b/chapter/windows.tex
index ce87618..7b7156e 100644
--- a/chapter/windows.tex
+++ b/chapter/windows.tex
@@ -150,7 +150,9 @@ \section{安装 \TeX{} Live}
   named COPYING and the TeX source.
   Primary author of TeX: D.E. Knuth.
 \end{lstlisting}
-即可认为安装顺利完成 \footnote{有用户反映安装后环境变量未发生变化, 则可手动添加 \texttt{<TEXDIR>\textbackslash bin\textbackslash win32} 至环境变量, \texttt{<TEXDIR>} 需与你方才的安装地址一致}. 
+即可认为安装顺利完成%
+\footnote{若未能正确显示结果, 则可能是因为环境变量未改变,
+用户可手动添加 \texttt{<TEXDIR>\textbackslash bin\textbackslash win32} 至环境变量, \texttt{<TEXDIR>} 需与你方才的安装地址一致}. 
 
 \subsection{下载镜像一直不成功的处理办法}