diff --git a/Makefile b/Makefile
index 7bebae3..2a10d26 100644
--- a/Makefile
+++ b/Makefile
@@ -246,7 +246,7 @@ LN := cp -l
 #
 DEPENDS.txt: $(MODULE).cls
 	cat $< \
-		| egrep -zo '\s*\\RequirePackage(\[[^]]*\])?\{[^}]*\}' \
+		| grep -Ezo '\s*\\RequirePackage(\[[^]]*\])?\{[^}]*\}' \
 		| sed 's/.*{\(.*\)}/hard \1\n/' \
 		| grep -a hard \
 		> $@
diff --git a/scripts/cls2tex.sh b/scripts/cls2tex.sh
index 34cf872..9119cd6 100755
--- a/scripts/cls2tex.sh
+++ b/scripts/cls2tex.sh
@@ -131,7 +131,7 @@ if [ -z $STRIP_DOC ] ; then
 	printmsg "Documentation" \
 		> "$OUTPUT"
 	cat "$INPUT" \
-		| egrep '(^%'$PREFIX'|^\\edef\\'$MODULE'@[A-Z][A-Z]+)' \
+		| grep -E '(^%'$PREFIX'|^\\edef\\'$MODULE'@[A-Z][A-Z]+)' \
 		| sed \
 			-e 's/^\(\\edef\\\)'$MODULE'@/%'$PREFIX'\1/' \
 			-e 's/%'$PREFIX'%%%% \(.*\)/%'$PREFIX'\\subsubsection{\1}\\label{subsubsec:\1}/' \
@@ -146,8 +146,8 @@ else
 	printmsg "Stripped code" \
 		> "$OUTPUT"
 	cat "$INPUT" \
-		| egrep -v '%'$PREFIX'' \
-		| egrep -v '^(\s*%)?\s*$' \
+		| grep -Ev '%'$PREFIX'' \
+		| grep -Ev '^(\s*%)?\s*$' \
 		>> "$OUTPUT"
 fi