diff --git a/homepage/knowledge/c78.html b/homepage/knowledge/c78.html
index 3956d5c..1705621 100644
--- a/homepage/knowledge/c78.html
+++ b/homepage/knowledge/c78.html
@@ -48,7 +48,7 @@ This page documents those incompatibilities and relative oddities.
 I have never done (and probably never will do) extensive programming in pre-ANSI C.
 These incompatibilities were discovered out of Appendix C in <I>The C Programming Language, 2nd ed.</I> but are described further.
 </P>
-<H2><CODE>8</CODE> and <CODE>9</CODE> as valid octal digits</H2>
+<H2 ID="octal89"><CODE>8</CODE> and <CODE>9</CODE> as valid octal digits</H2>
 <PRE>
 main()
 {