getNetworkPrefixLength() returns strange subnet mask

The following code:

Code:

---

InetAddress localHost = Inet4Address.getLocalHost();
NetworkInterface networkInterface = NetworkInterface.getByInetAddress(localHost);

for (InterfaceAddress address : networkInterface.getInterfaceAddresses()) {
    System.out.println(address.getAddress() + "/" + address.getNetworkPrefixLength());
}

---

returns:

Code:

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/fe80:0:0:0:11da:433a:412a:8c23%13/64
/192.168.1.107/128

---

My subnet mask is /24, not /128. Is it a Java bug?