diff --git a/make/tex.mk b/make/tex.mk
index 00a4fa8d..f3d27184 100644
--- a/make/tex.mk
+++ b/make/tex.mk
@@ -103,6 +103,13 @@ define mangle_tmpl
 		s%ü%\"u%g; \
 		s%Ü%\"U%g; \
 		s%ß%\"s%g; \
+		s%\xc3\xa4%\"a%g; \
+		s%\xc3\x84%\"A%g; \
+		s%\xc3\xb6%\"o%g; \
+		s%\xc3\x96%\"O%g; \
+		s%\xc3\xbc%\"u%g; \
+		s%\xc3\x9c%\"U%g; \
+		s%\xc3\x9f%\"s%g; \
 	" | awk '                                              \
 		BEGIN { FS=":" } {                             \
 		if ($$0 ~ /SUBST_LINE_NUM/) {                  \