diff --git a/router/java/src/net/i2p/router/transport/udp/EstablishmentManager.java b/router/java/src/net/i2p/router/transport/udp/EstablishmentManager.java
index 681902f8d..c0b4bd134 100644
--- a/router/java/src/net/i2p/router/transport/udp/EstablishmentManager.java
+++ b/router/java/src/net/i2p/router/transport/udp/EstablishmentManager.java
@@ -2825,6 +2825,14 @@ class EstablishmentManager {
         public void gotTermination(int reason, long count) {
             throw new IllegalStateException("Bad block in HP");
         }
+
+        public void gotPathChallenge(byte[] data) {
+            throw new IllegalStateException("Bad block in HP");
+        }
+
+        public void gotPathResponse(byte[] data) {
+            throw new IllegalStateException("Bad block in HP");
+        }
     }
 
 
diff --git a/router/java/src/net/i2p/router/transport/udp/InboundEstablishState2.java b/router/java/src/net/i2p/router/transport/udp/InboundEstablishState2.java
index a2c3f0c0c..18c96dc9d 100644
--- a/router/java/src/net/i2p/router/transport/udp/InboundEstablishState2.java
+++ b/router/java/src/net/i2p/router/transport/udp/InboundEstablishState2.java
@@ -420,6 +420,14 @@ class InboundEstablishState2 extends InboundEstablishState implements SSU2Payloa
         _transport.getEstablisher().receiveSessionDestroy(_remoteHostId);
     }
 
+    public void gotPathChallenge(byte[] data) {
+        throw new IllegalStateException("Bad block in handshake");
+    }
+
+    public void gotPathResponse(byte[] data) {
+        throw new IllegalStateException("Bad block in handshake");
+    }
+
     /////////////////////////////////////////////////////////
     // end payload callbacks
     /////////////////////////////////////////////////////////
diff --git a/router/java/src/net/i2p/router/transport/udp/OutboundEstablishState2.java b/router/java/src/net/i2p/router/transport/udp/OutboundEstablishState2.java
index d77aafe6d..3f6b299a4 100644
--- a/router/java/src/net/i2p/router/transport/udp/OutboundEstablishState2.java
+++ b/router/java/src/net/i2p/router/transport/udp/OutboundEstablishState2.java
@@ -348,6 +348,14 @@ class OutboundEstablishState2 extends OutboundEstablishState implements SSU2Payl
         _transport.getEstablisher().receiveSessionDestroy(_remoteHostId, this);
     }
 
+    public void gotPathChallenge(byte[] data) {
+        // won't be called, SSU2Payload will throw
+    }
+
+    public void gotPathResponse(byte[] data) {
+        // won't be called, SSU2Payload will throw
+    }
+
     /////////////////////////////////////////////////////////
     // end payload callbacks
     /////////////////////////////////////////////////////////
diff --git a/router/java/src/net/i2p/router/transport/udp/PeerState2.java b/router/java/src/net/i2p/router/transport/udp/PeerState2.java
index cbd6451ba..d05d859d5 100644
--- a/router/java/src/net/i2p/router/transport/udp/PeerState2.java
+++ b/router/java/src/net/i2p/router/transport/udp/PeerState2.java
@@ -637,6 +637,14 @@ public class PeerState2 extends PeerState implements SSU2Payload.PayloadCallback
         _transport.getEstablisher().receiveSessionDestroy(_remoteHostId, this);
     }
 
+    public void gotPathChallenge(byte[] data) {
+        // TODO
+    }
+
+    public void gotPathResponse(byte[] data) {
+        // TODO
+    }
+
     /////////////////////////////////////////////////////////
     // end payload callbacks
     /////////////////////////////////////////////////////////
diff --git a/router/java/src/net/i2p/router/transport/udp/PeerTestManager.java b/router/java/src/net/i2p/router/transport/udp/PeerTestManager.java
index 8a130adcd..d1bb0f659 100644
--- a/router/java/src/net/i2p/router/transport/udp/PeerTestManager.java
+++ b/router/java/src/net/i2p/router/transport/udp/PeerTestManager.java
@@ -1837,6 +1837,9 @@ class PeerTestManager {
     }
 
     /**
+     *  This is only for out-of-session messages 5-7,
+     *  where most blocks are not allowed.
+     *
      *  @since 0.9.54
      */
     private class PTCallback implements SSU2Payload.PayloadCallback {
@@ -1920,5 +1923,13 @@ class PeerTestManager {
         public void gotTermination(int reason, long count) {
             throw new IllegalStateException("Bad block in PT");
         }
+
+        public void gotPathChallenge(byte[] data) {
+            throw new IllegalStateException("Bad block in PT");
+        }
+
+        public void gotPathResponse(byte[] data) {
+            throw new IllegalStateException("Bad block in PT");
+        }
     }
 }
diff --git a/router/java/src/net/i2p/router/transport/udp/SSU2Payload.java b/router/java/src/net/i2p/router/transport/udp/SSU2Payload.java
index 50348817c..2f5ba0b46 100644
--- a/router/java/src/net/i2p/router/transport/udp/SSU2Payload.java
+++ b/router/java/src/net/i2p/router/transport/udp/SSU2Payload.java
@@ -124,6 +124,16 @@ class SSU2Payload {
          *  @param lastReceived in theory could wrap around to negative, but very unlikely
          */
         public void gotTermination(int reason, long lastReceived);
+
+        /**
+         *  @since 0.9.55
+         */
+        public void gotPathChallenge(byte[] data);
+
+        /**
+         *  @since 0.9.55
+         */
+        public void gotPathResponse(byte[] data);
     }
 
     /**
@@ -352,6 +362,22 @@ class SSU2Payload {
                     gotTermination = true;
                     break;
 
+                case BLOCK_PATHCHALLENGE:
+                    if (isHandshake)
+                        throw new IOException("Illegal block in handshake: " + type);
+                    byte[] cdata = new byte[len];
+                    System.arraycopy(payload, i, cdata, 0, len);
+                    cb.gotPathChallenge(cdata);
+                    break;
+
+                case BLOCK_PATHRESP:
+                    if (isHandshake)
+                        throw new IOException("Illegal block in handshake: " + type);
+                    byte[] rdata = new byte[len];
+                    System.arraycopy(payload, i, rdata, 0, len);
+                    cb.gotPathResponse(rdata);
+                    break;
+
                 case BLOCK_PADDING:
                     gotPadding = true;
                     break;