diff --git a/helper/helper/oath.py b/helper/helper/oath.py
index 32718e35..5aaccaea 100644
--- a/helper/helper/oath.py
+++ b/helper/helper/oath.py
@@ -91,6 +91,7 @@ class OathNode(RpcNode):
     def __init__(self, connection):
         super().__init__()
         self.session = OathSession(connection)
+        self._key_verifier = None
 
         if self.session.locked:
             key = self._get_access_key(self.session.device_id)
@@ -162,12 +163,15 @@ class OathNode(RpcNode):
             return decode_bytes(params.pop("key"))
         raise ValueError("One of 'key' and 'password' must be provided.")
 
-    def _do_validate(self, key):
-        self.session.validate(key)
+    def _set_key_verifier(self, key):
         salt = os.urandom(32)
         digest = hmac.new(salt, key, "sha256").digest()
         self._key_verifier = (salt, digest)
 
+    def _do_validate(self, key):
+        self.session.validate(key)
+        self._set_key_verifier(key)
+
     @action
     def validate(self, params, event, signal):
         remember = params.pop("remember", False)
@@ -181,7 +185,7 @@ class OathNode(RpcNode):
                     valid = False
                 else:
                     raise e
-        elif hasattr(self, "_key_verifier"):
+        elif self._key_verifier:
             salt, digest = self._key_verifier
             verify = hmac.new(salt, key, "sha256").digest()
             valid = hmac.compare_digest(digest, verify)
@@ -198,18 +202,21 @@ class OathNode(RpcNode):
         remember = params.pop("remember", False)
         key = self._get_key(params)
         self.session.set_key(key)
+        self._set_key_verifier(key)
         remember &= self._remember_key(key if remember else None)
         return dict(remembered=remember)
 
     @action(condition=lambda self: self.session.has_key)
     def unset_key(self, params, event, signal):
         self.session.unset_key()
+        self._key_verifier = None
         self._remember_key(None)
         return dict()
 
     @action
     def reset(self, params, event, signal):
         self.session.reset()
+        self._key_verifier = None
         self._remember_key(None)
         return dict()