diff --git a/ptbletter/ptbletter-doc.tex b/ptbletter/ptbletter-doc.tex
index d10b53839d10de8f727d3c8849e8d88060f17cfa..d00f05bddb41f52dd3874473e39f6093e94c94c3 100644
--- a/ptbletter/ptbletter-doc.tex
+++ b/ptbletter/ptbletter-doc.tex
@@ -2,7 +2,7 @@
 \documentclass[%
 ,ngerman
 ,twoside
-,serif
+%,serif
 ,sanserif
 ,BLN
 %,BS