diff --git a/ptbposter/ptbposter-new-engines.clo b/ptbposter/ptbposter-new-engines.clo
index e31eb158c7c424b7a8adca57959121109efc7ddf..41df30d6140c6e079bcc88471097922bd6df9b3e 100644
--- a/ptbposter/ptbposter-new-engines.clo
+++ b/ptbposter/ptbposter-new-engines.clo
@@ -37,10 +37,13 @@
     bold-style=TeX,
   ]
 \else
-  %%%\RequirePackage[usefilenames,weight=Regular]{firamath-otf}
-  %%%\setoperatorfont\mathsf 
-  %%%\unimathsetup{partial=upright}%
-  \RequirePackage{newtxsf}
+  \iftrue
+    \usepackage[usefilenames,weight=Regular]{firamath-otf}
+    \setoperatorfont\mathsf 
+    \unimathsetup{partial=upright}%  
+  \else
+    \usepackage{newtxsf}
+  \fi
 \fi
 
 \renewcommand*\familydefault{\sfdefault}%