diff --git a/ptbposter/ptbposter-new-engines.clo b/ptbposter/ptbposter-new-engines.clo
index 1dc81a079c7d285488f853eb4d99999857c64c4b..56d9677024f34bc09d2bbaabd2253f17168cf4e3 100644
--- a/ptbposter/ptbposter-new-engines.clo
+++ b/ptbposter/ptbposter-new-engines.clo
@@ -31,7 +31,7 @@
 \else
   \renewcommand*\familydefault{\sfdefault} 
   \RequirePackage[usefilenames,weight=Regular]{firamath-otf}
-  \RequirePackage[italic]{mathastext}  
+  \setmathfont[range=it]{texgyreheros-italic.otf}  
 \fi
 \RequirePackage{newunicodechar}
 \newunicodechar{^^^^202f}{\,}% 'NARROW NO-BREAK SPACE' (\u202F, 8239)