diff --git a/ptbposter/ptbposter.cls b/ptbposter/ptbposter.cls
index 42269a1f676f6ce38a4b03ed3732ea245def488d..67339b52997c5389faccebe7d811b0f07e555e83 100644
--- a/ptbposter/ptbposter.cls
+++ b/ptbposter/ptbposter.cls
@@ -140,21 +140,36 @@
 
 \@ifundefined{changefontsizes}{%
   \ClassError{ptbposter}{%
-    Deine Version von KOMA-Script ist ungeeignet (vermutlich stark veraltet)!
+    Your version of KOMA-Script is unsuitable\MessageBreak
+    (probably very outdated)!
   }{%
-    Installiere die aktuelle Version von KOMA-Script.
+    Install the latest version of KOMA-Script.
   }%
+  \@@end
 }{}
 
-\ifx\PTB@target@size\@empty\else
-  \RequirePackage{blowup}[2022/09/19]
-  \ClassNoteNoLine{ptbposter}{%
-    Scaling the sheet from size `a0' to size `\PTB@target@size'}%
-  \ifPTBlandscape
-    \blowUp{target=\PTB@target@size,landscape}
-  \else
-    \blowUp{target=\PTB@target@size}
-  \fi
+\ifx\PTB@target@size\@empty\else % Sheet scaling is necessary
+  \RequirePackage{blowup}
+  \IfPackageAtLeastTF{blowup}{2022/09/19}{%
+    \RequirePackage{blowup}%
+    \ClassNoteNoLine{ptbposter}{%
+      Scaling the sheet from size `a0' to size `\PTB@target@size'}%
+    \ifPTBlandscape
+      \blowUp{target=\PTB@target@size,landscape}
+    \else
+      \blowUp{target=\PTB@target@size}
+    \fi
+  }{%
+    \ClassError{ptbposter}{%
+      You need version `2022/09/19' or newer of the \MessageBreak
+      `blowup' package to scale the document, but only \MessageBreak
+      version `\csname ver@blowup.sty\endcsname' \MessageBreak
+      is available
+    }{%
+      Install the latest version of `blowup'.
+    }%
+    \@@end
+  }
 \fi
 
 \iftutex% LuaTeX oder XeTeX
diff --git a/ptbposter/tcb-example1.pdf b/ptbposter/tcb-example1.pdf
index 817eda45362c156d54e8a15298b9471c63224fb8..0f36e478d65b21c51baab9c4de5ae9f799d0c85d 100644
Binary files a/ptbposter/tcb-example1.pdf and b/ptbposter/tcb-example1.pdf differ
diff --git a/ptbposter/tcb-example1.tex b/ptbposter/tcb-example1.tex
index 4da6009813309a7a09af7e19c6d1f3cbd6bcd398..fded5994010727a8d4cf0b444a3098e1469a2e82 100644
--- a/ptbposter/tcb-example1.tex
+++ b/ptbposter/tcb-example1.tex
@@ -1,6 +1,6 @@
 \documentclass[%
 ,sanserif
-%,a4paper
+,a4paper
 ]{ptbposter}
 
 \usepackage[