fix some markup errors
diff --git a/Doc/lib/libbase64.tex b/Doc/lib/libbase64.tex
index d7eccbd..23b74f0 100644
--- a/Doc/lib/libbase64.tex
+++ b/Doc/lib/libbase64.tex
@@ -85,7 +85,7 @@
letter O (oh), and for optional mapping of the digit 1 (one) to either
the letter I (eye) or letter L (el). The optional argument
\var{map01} when not \code{None}, specifies which letter the digit 1 should
-be mapped to (when map01 is not \var{None}, the digit 0 is always
+be mapped to (when \var{map01} is not \code{None}, the digit 0 is always
mapped to the letter O). For security purposes the default is
\code{None}, so that 0 and 1 are not allowed in the input.