diff --git a/src/HsH-article.cls b/src/HsH-article.cls
index 92d98746481b2860a6b1b050c029643412379fcb..93c26ffef18dbe5927da654fbd831a1a1114a099 100644
--- a/src/HsH-article.cls
+++ b/src/HsH-article.cls
@@ -180,7 +180,9 @@
 % load config at beginning of document
 \AtBeginDocument{
 	\makeatletter
-	\renewcommand*{\mkbibacro}[1]{\MakeUppercase{#1}} % solves fontype warning in San-Serif
+	\@ifpackageloaded{biblatex}{
+		\renewcommand*{\mkbibacro}[1]{\MakeUppercase{#1}} % solves fontype warning in San-Serif
+	}{}%
 	\@ifpackageloaded{subfigure}{
 		\newcommand{\subfigureautorefname}{\figureautorefname}
 	}{}%
diff --git a/src/HsH-report.cls b/src/HsH-report.cls
index 4ffefc64a90b1ca807732e7a20f68428df8f67f0..597f35ebb81648f3fc22d87fe4289424a09844a9 100644
--- a/src/HsH-report.cls
+++ b/src/HsH-report.cls
@@ -190,7 +190,9 @@
 % load config at beginning of document
 \AtBeginDocument{
 	\makeatletter
-	\renewcommand*{\mkbibacro}[1]{\MakeUppercase{#1}} % solves fontype warning in San-Serif
+	\@ifpackageloaded{biblatex}{
+		\renewcommand*{\mkbibacro}[1]{\MakeUppercase{#1}} % solves fontype warning in San-Serif
+	}{}%
 	\@ifpackageloaded{subfigure}{
 		\newcommand{\subfigureautorefname}{\figureautorefname}
 	}{}%