diff --git a/chapter4_interactive_prompt.html b/chapter4_interactive_prompt.html
index eb550c7..f858a4a 100644
--- a/chapter4_interactive_prompt.html
+++ b/chapter4_interactive_prompt.html
@@ -121,6 +121,7 @@ <h3>Using Editline</h3>
 #include &lt;stdlib.h&gt;
 
 #include &lt;editline/readline.h&gt;
+// Do not include history.h for MacOS X or later
 #include &lt;editline/history.h&gt;
 
 int main(int argc, char** argv) {