diff --git a/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/udp/I2PSink.java b/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/udp/I2PSink.java
index 6a32801b7..f7a1bf541 100644
--- a/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/udp/I2PSink.java
+++ b/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/udp/I2PSink.java
@@ -37,9 +37,11 @@ public class I2PSink implements Sink {
         //System.out.print("w");
         // create payload
         byte[] payload;
-        if(!this.raw)
-            payload = this.maker.makeI2PDatagram(data);
-        else
+        if(!this.raw) {
+            synchronized(this.maker) {
+                payload = this.maker.makeI2PDatagram(data);
+            }
+        } else
             payload = data;
         
         // send message
diff --git a/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/udp/I2PSinkAnywhere.java b/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/udp/I2PSinkAnywhere.java
index 8707d9779..54d5a7d97 100644
--- a/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/udp/I2PSinkAnywhere.java
+++ b/apps/i2ptunnel/java/src/net/i2p/i2ptunnel/udp/I2PSinkAnywhere.java
@@ -35,9 +35,11 @@ public class I2PSinkAnywhere implements Sink {
     public synchronized void send(Destination to, byte[] data) {
         // create payload
         byte[] payload;
-        if(!this.raw)
-            payload = this.maker.makeI2PDatagram(data);
-        else
+        if(!this.raw) {
+            synchronized(this.maker) {
+                payload = this.maker.makeI2PDatagram(data);
+            }
+        } else
             payload = data;
         
         // send message