diff --git a/README.md b/README.md
index 4e297c0..757261d 100644
--- a/README.md
+++ b/README.md
@@ -1631,7 +1631,7 @@ import os, shutil
 
 ```python
 os.chdir(<path>)                    # Changes current working directory.
-os.mkdir(<path>, mode=0o777)        # Creates a directory.
+os.mkdir(<path>, mode=0o777)        # Creates a directory. Mode is in octal.
 ```
 
 ```python
diff --git a/index.html b/index.html
index 61ad9a4..863d900 100644
--- a/index.html
+++ b/index.html
@@ -1490,7 +1490,7 @@ value = args.&lt;name&gt;
 
 
 <pre><code class="python language-python hljs">os.chdir(&lt;path&gt;)                    <span class="hljs-comment"># Changes current working directory.</span>
-os.mkdir(&lt;path&gt;, mode=<span class="hljs-number">0o777</span>)        <span class="hljs-comment"># Creates a directory.</span>
+os.mkdir(&lt;path&gt;, mode=<span class="hljs-number">0o777</span>)        <span class="hljs-comment"># Creates a directory. Mode is in octal.</span>
 </code></pre>
 <pre><code class="python language-python hljs">shutil.copy(from, to)               <span class="hljs-comment"># Copies the file.</span>
 shutil.copytree(from, to)           <span class="hljs-comment"># Copies the entire directory tree.</span>