diff --git a/doc/scsh-manual/procnotation.tex b/doc/scsh-manual/procnotation.tex
index 780e651..8761c29 100644
--- a/doc/scsh-manual/procnotation.tex
+++ b/doc/scsh-manual/procnotation.tex
@@ -529,7 +529,7 @@ text streams.
      (> spell-errors.txt))\end{code}
 \end{defundesc}
 
-\beginz{defundesc}{make-string-port-filter}{filter [buflen]}{\proc}
+\begin{defundesc}{make-string-port-filter}{filter [buflen]}{\proc}
     The \var{filter} argument is a string$\rightarrow$string procedure.
     Returns a procedure that when called, repeatedly reads a string
     from the current input port, applies \var{filter} to the string,