diff --git a/ptbletter/ptbletter.cls b/ptbletter/ptbletter.cls
index 0690c1eee3cb17a74b34dca483c6c3abe456fb68..818089af83bfe3a91517b2a5d291b26856d090a7 100644
--- a/ptbletter/ptbletter.cls
+++ b/ptbletter/ptbletter.cls
@@ -157,7 +157,7 @@
 \@setplength{subjectaftervskip}{23bp}
 
 \@setplength{sigindent}{3em}
-\@setplength{sigbeforevskip}{-20mm}% ???
+\@setplength{sigbeforevskip}{-17.2mm}% ???
 \setlength{\textheight}{230mm}
 \setlength{\footskip}{3\baselineskip}
 \setlength{\footheight}{0mm}% ???