diff --git a/src/avalanche/delegationbuilder.cpp b/src/avalanche/delegationbuilder.cpp
--- a/src/avalanche/delegationbuilder.cpp
+++ b/src/avalanche/delegationbuilder.cpp
@@ -37,8 +37,10 @@
 }
 
 bool DelegationBuilder::addLevel(const CKey &key, const CPubKey &master) {
-    // Ensures that the private key provided is the one we need.
-    if (levels.back().pubkey != key.GetPubKey()) {
+    // Ensures that the private key provided is the one we need and we're not
+    // delegating to the same public key.
+    const CPubKey &currentPubKey = levels.back().pubkey;
+    if (currentPubKey != key.GetPubKey() || currentPubKey == master) {
         return false;
     }
 
diff --git a/src/avalanche/processor.cpp b/src/avalanche/processor.cpp
--- a/src/avalanche/processor.cpp
+++ b/src/avalanche/processor.cpp
@@ -251,8 +251,9 @@
 
         // Generate the delegation to the session key.
         DelegationBuilder dgb(peerData->proof);
-        if (sessionKey.GetPubKey() != peerData->proof.getMaster()) {
-            dgb.addLevel(masterKey, sessionKey.GetPubKey());
+        if (!dgb.addLevel(masterKey, sessionKey.GetPubKey())) {
+            error = _("failed to add a level of delegation");
+            return nullptr;
         }
         peerData->delegation = dgb.build();
     }
diff --git a/test/functional/abc_rpc_avalancheproof.py b/test/functional/abc_rpc_avalancheproof.py
--- a/test/functional/abc_rpc_avalancheproof.py
+++ b/test/functional/abc_rpc_avalancheproof.py
@@ -209,6 +209,25 @@
             expected_msg="Error: the avalanche master key is invalid",
         )
 
+        # Wrong key
+        node.assert_start_raises_init_error(
+            self.extra_args[0] + [
+                "-avaproof={}".format(proof),
+                "-avamasterkey=cN55daf1HotwBAgAKWVgDcoppmUNDtQSfb7XLutTLeAgVc3u8hik",
+            ],
+            expected_msg="Error: failed to add a level of delegation",
+        )
+
+        # Delegating to self
+        node.assert_start_raises_init_error(
+            self.extra_args[0] + [
+                "-avaproof={}".format(proof),
+                "-avamasterkey=cND2ZvtabDbJ1gucx9GWH6XT9kgTAqfb6cotPt5Q5CyxVDhid2EN",
+                "-avasessionkey=cND2ZvtabDbJ1gucx9GWH6XT9kgTAqfb6cotPt5Q5CyxVDhid2EN",
+            ],
+            expected_msg="Error: failed to add a level of delegation",
+        )
+
         def check_proof_init_error(proof, message):
             node.assert_start_raises_init_error(
                 self.extra_args[0] + [