diff --git a/samples/pktgen/functions.sh b/samples/pktgen/functions.sh
index 933194257a24..dd4e53ae9b73 100644
--- a/samples/pktgen/functions.sh
+++ b/samples/pktgen/functions.sh
@@ -191,7 +191,7 @@ function extend_addr6()
     fi
 
     # if shrink '::' occurs multiple, it's malformed.
-    shrink=( $(egrep -o "$sep{2,}" <<< $addr) )
+    shrink=( $(grep -E -o "$sep{2,}" <<< $addr) )
     if [[ ${#shrink[@]} -ne 0 ]]; then
         if [[ ${#shrink[@]} -gt 1 || ( ${shrink[0]} != $sep2 ) ]]; then
             err 5 "Invalid IP6 address: $1"