diff --git a/contrib/ipv6calc b/contrib/ipv6calc
index 142e19ec..dca4c144 100644
--- a/contrib/ipv6calc
+++ b/contrib/ipv6calc
@@ -14,7 +14,8 @@ _ipv6calc()
             return 0
             ;;
         -I|--in|-O|--out|-A|--action)
-            COMPREPLY=( $( compgen -W "$( ipv6calc -m "$prev" -h 2>&1 | \
+            # With ipv6calc < 0.73.0, -m does nothing here, so use sed instead.
+            COMPREPLY=( $( compgen -W "$( ipv6calc "$prev" -h 2>&1 | \
                 sed -ne 's/^[[:space:]]\{1,\}\([^[:space:]:]\{1,\}\)[[:space:]]*:.*/\1/p' )" \
                 -- "$cur" ) )
             return 0