diff --git a/Modules/main.c b/Modules/main.c
index 3e7e065..d129aba 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -99,6 +99,7 @@
                The default module search path uses %s.\n\
 PYTHONCASEOK : ignore case in 'import' statements (Windows).\n\
 PYTHONIOENCODING: Encoding[:errors] used for stdin/stdout/stderr.\n\
+PYTHONFSENCODING: Encoding used for the filesystem.\n\
 ";
 
 FILE *