diff --git a/doc/install.doc b/doc/install.doc
index f09d7709f..be1134a01 100644
--- a/doc/install.doc
+++ b/doc/install.doc
@@ -251,6 +251,10 @@ excluding Stdio
 .IP "lang/cem/libcc/stdio"
 .br
 Stdio sources
+.IP "lang/cem/libcc/math"
+.br
+Sources for mathematical routines, normally available with the
+\fB-lm\fP option to \fIcc\fP.
 .IP "lang/cem/libcc/mon"
 .br
 Sources for routines in chapter II, written in EM