diff --git a/router/java/src/org/cybergarage/upnp/ssdp/HTTPUSocket.java b/router/java/src/org/cybergarage/upnp/ssdp/HTTPUSocket.java
index c21f452e3d457024a933b7b8cf04c73ca7f5c8e0..65f8b7302a3cb5dea29be6e5dad764078bc8e796 100644
--- a/router/java/src/org/cybergarage/upnp/ssdp/HTTPUSocket.java
+++ b/router/java/src/org/cybergarage/upnp/ssdp/HTTPUSocket.java
@@ -92,6 +92,9 @@ public class HTTPUSocket
 	{
 		if (0 < localAddr.length())
 			return localAddr;
+		// I2P prevent NPE #1681
+		if (ssdpUniSock == null)
+			return "";
 		return ssdpUniSock.getLocalAddress().getHostAddress();
 	}