diff --git a/cmd/sriov/main.go b/cmd/sriov/main.go
index 93784e051..616fb185c 100644
--- a/cmd/sriov/main.go
+++ b/cmd/sriov/main.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"runtime"
+	"strings"
 
 	"github.com/containernetworking/cni/pkg/skel"
 	"github.com/containernetworking/cni/pkg/types"
@@ -66,6 +67,9 @@ func cmdAdd(args *skel.CmdArgs) error {
 		netConf.MAC = netConf.RuntimeConfig.Mac
 	}
 
+	// Always use lower case for mac address
+	netConf.MAC = strings.ToLower(netConf.MAC)
+
 	netns, err := ns.GetNS(args.Netns)
 	if err != nil {
 		return fmt.Errorf("failed to open netns %q: %v", netns, err)