diff --git a/lectures/Makefile b/lectures/Makefile
index eebc9e8..7364a67 100644
--- a/lectures/Makefile
+++ b/lectures/Makefile
@@ -2,8 +2,8 @@
 # maybe this helps: https://stackoverflow.com/questions/6278057/replace-only-first-match-in-multiple-files-with-perl
 
 %-handout.pdf: %.tex
-	cat $< | sed -e 's/^\\documentclass\[/\\documentclass\[handout,/' -e 's/^\\documentclass{/\\documentclass\[handout\]{/' | lualatex -jobname=$(basename $@)
-	cat $< | sed -e 's/^\\documentclass\[/\\documentclass\[handout,/' -e 's/^\\documentclass{/\\documentclass\[handout\]{/' | lualatex -jobname=$(basename $@)
+	cat $< | perl -0777 -p -e 's/^\\documentclass\[/\\documentclass\[handout,/' -e 's/^\\documentclass{/\\documentclass\[handout\]{/' | lualatex -jobname=$(basename $@)
+	cat $< | perl -0777 -p -e 's/^\\documentclass\[/\\documentclass\[handout,/' -e 's/^\\documentclass{/\\documentclass\[handout\]{/' | lualatex -jobname=$(basename $@)
 
 clean:
 	rm -f *-handout.pdf