diff --git a/internal/testutil/testutil.go b/internal/testutil/testutil.go
index 2bba58e..8f182be 100644
--- a/internal/testutil/testutil.go
+++ b/internal/testutil/testutil.go
@@ -64,6 +64,10 @@ func (sn Snake) Check(data []byte) (ok bool, n int) {
 }
 
 func (sn Snake) String() string {
+	if len(sn) == 0 || len(sn[0]) == 0 || len(sn[0][0]) == 0{
+		return "EMPTY"
+	}
+
 	out := strings.Builder { }
 	for index, sector := range sn {
 		if index > 0 { out.WriteString(" : ") }
@@ -81,6 +85,7 @@ func (sn Snake) String() string {
 
 // HexBytes formats bytes into a hexadecimal string.
 func HexBytes(data []byte) string {
+	if len(data) == 0 { return "EMPTY" }
 	out := strings.Builder { }
 	for _, byt := range data {
 		fmt.Fprintf(&out, "%02x", byt)