diff --git a/acme.sh b/acme.sh
index ce6796b1..6bb57afb 100755
--- a/acme.sh
+++ b/acme.sh
@@ -798,7 +798,7 @@ _sed_i() {
 }
 
 _egrep_o() {
-  if ! egrep -o "$1" 2>/dev/null; then
+  if ! grep -E -o "$1" 2>/dev/null; then
     sed -n 's/.*\('"$1"'\).*/\1/p'
   fi
 }