diff --git a/laymanshex.go b/laymanshex.go
index a7f1a9b..ef4e284 100644
--- a/laymanshex.go
+++ b/laymanshex.go
@@ -173,6 +173,7 @@ func (part *filePart) setHandling() {
 			return hex.EncodeToString(buf)
 		}
 		writeTo := func(w io.Writer, bo binary.ByteOrder, s string) {
+			s = strings.TrimPrefix(s, "0x")
 			buf, err := hex.DecodeString(s)
 			optPanic("invalid string of hex values: "+s, err)
 			if int64(len(buf)) > bytes {