diff --git a/Doc/whatsnew/whatsnew21.tex b/Doc/whatsnew/whatsnew21.tex
index 8ba1e10..948d43a 100644
--- a/Doc/whatsnew/whatsnew21.tex
+++ b/Doc/whatsnew/whatsnew21.tex
@@ -511,7 +511,7 @@
 search for the first case-sensitive match by default, raising an
 \exception{ImportError} if no such file is found, so \code{import file}
 will not import a module named \samp{FILE.PY}.  Case-insensitive
-matching can be requested by setting the PYTHONCASEOK environment
+matching can be requested by setting the \envvar{PYTHONCASEOK} environment
 variable before starting the Python interpreter.
 
 %======================================================================