diff --git a/ks-new-engines.clo b/ks-new-engines.clo
index 6e7448bcc0c04f9ee01d171e6cb19cff039a2798..b8245c41710c84c4615e466cb509a270e4a1f9ad 100644
--- a/ks-new-engines.clo
+++ b/ks-new-engines.clo
@@ -3,33 +3,44 @@
 \ProvidesFile{ks-new-engines.clo}%
   [2020/09/14 v0.1f PTB `Kalibrierschein' new engines (RN/PTB)]
 
-\RequirePackage{unicode-math}
+\RequirePackage[no-math]{fontspec}
 \setsansfont{texgyreheros}[
   Ligatures=TeX,
   Extension=.otf,
   UprightFont=*-regular,
   BoldFont=*-bold,
   ItalicFont=*-italic,
-  BoldItalicFont=*-bolditalic]
+  BoldItalicFont=*-bolditalic] 
+  
 \renewcommand*\familydefault{\sfdefault}
+
 \setmonofont{AnonymousPro-Regular}[%
   Extension = .ttf,
   BoldFont = AnonymousPro-Bold,
   ItalicFont = AnonymousPro-Italic,
   BoldItalicFont = AnonymousPro-BoldItalic,
-  Scale     = MatchUppercase] 
-\RequirePackage[usefilenames,weight=Regular]{firamath-otf}
-\iffalse
-\RequirePackage[italic]{mathastext}
-% Abstandskorrektur; Bug-Report an Autor von "mathastext"?  
-\def\prim@s{\/\prime\futurelet\@let@token\pr@m@s}
-\AtBeginDocument{\let\PRIME\prime
-  \def\prime{\mkern2mu\PRIME}%
-}
-\else
-%\setmathfont[range=it]{texgyreheros-italic.otf}% führte zu falsch pos. \dot!
-\setoperatorfont\mathsf
-\fi
+  Scale     = 1.05, 
+  RawFeature={embolden=.5}
+]
+  
+\RequirePackage{unicode-math} 
+\setmathfont{FiraMath-Regular.otf}[
+  Scale=1,
+  math-style=TeX,
+  bold-style=TeX,
+  Numbers={Lining,Proportional},
+]
+\unimathsetup{%
+  math-style = TeX,
+  bold-style = TeX,
+  mathrm     = sym,
+  partial=upright              
+} 
+\setoperatorfont\mathsf 
+\setmathfont{texgyreheros-regular.otf}[range=up/{Latin,Greek,num}]
+\setmathfont{texgyreheros-italic.otf}[range=it/{latin,greek}]
+\setmathfont{texgyreheros-bolditalic.otf}[range=bfit/{latin,greek}]
+\setmathfont{texgyreheros-bold.otf}[range=bfup/{latin,greek}]
 
 \RequirePackage{newunicodechar}
 \newunicodechar{^^^^202f}{\,}% 'NARROW NO-BREAK SPACE' (\u202F, 8239)