diff --git a/api/models/profile/TwoFactorAuthForm.php b/api/models/profile/TwoFactorAuthForm.php
index 02c1734..126186c 100644
--- a/api/models/profile/TwoFactorAuthForm.php
+++ b/api/models/profile/TwoFactorAuthForm.php
@@ -23,6 +23,8 @@ class TwoFactorAuthForm extends ApiForm {
 
     public $token;
 
+    public $timestamp;
+
     public $password;
 
     /**
@@ -38,10 +40,16 @@ class TwoFactorAuthForm extends ApiForm {
     public function rules() {
         $bothScenarios = [self::SCENARIO_ACTIVATE, self::SCENARIO_DISABLE];
         return [
+            ['timestamp', 'integer', 'on' => [self::SCENARIO_ACTIVATE]],
             ['account', 'validateOtpDisabled', 'on' => self::SCENARIO_ACTIVATE],
             ['account', 'validateOtpEnabled', 'on' => self::SCENARIO_DISABLE],
             ['token', 'required', 'message' => E::OTP_TOKEN_REQUIRED, 'on' => $bothScenarios],
-            ['token', TotpValidator::class, 'account' => $this->account, 'window' => 30, 'on' => $bothScenarios],
+            ['token', TotpValidator::class, 'on' => $bothScenarios,
+                'account' => $this->account,
+                'timestamp' => function() {
+                    return $this->timestamp;
+                },
+            ],
             ['password', PasswordRequiredValidator::class, 'account' => $this->account, 'on' => $bothScenarios],
         ];
     }
diff --git a/api/validators/TotpValidator.php b/api/validators/TotpValidator.php
index dac0c17..9b5f277 100644
--- a/api/validators/TotpValidator.php
+++ b/api/validators/TotpValidator.php
@@ -19,9 +19,17 @@ class TotpValidator extends Validator {
      * @var int|null Задаёт окно, в промежуток которого будет проверяться код.
      * Позволяет избежать ситуации, когда пользователь ввёл код в последнюю секунду
      * его существования и пока шёл запрос, тот протух.
+     * Значение задаётся в +- кодах, а не секундах.
      */
     public $window;
 
+    /**
+     * @var int|callable|null Позволяет задать точное время, относительно которого будет
+     * выполняться проверка. Это может быть собственно время или функция, возвращающая значение.
+     * Если не задано, то будет использовано текущее время.
+     */
+    public $timestamp;
+
     public $skipOnEmpty = false;
 
     public function init() {
@@ -41,11 +49,23 @@ class TotpValidator extends Validator {
 
     protected function validateValue($value) {
         $totp = new TOTP(null, $this->account->otp_secret);
-        if (!$totp->verify((string)$value, null, $this->window)) {
+        if (!$totp->verify((string)$value, $this->getTimestamp(), $this->window)) {
             return [E::OTP_TOKEN_INCORRECT, []];
         }
 
         return null;
     }
 
+    private function getTimestamp(): ?int {
+        if ($this->timestamp === null) {
+            return null;
+        }
+
+        if (is_callable($this->timestamp)) {
+            return (int)call_user_func($this->timestamp);
+        }
+
+        return (int)$this->timestamp;
+    }
+
 }
diff --git a/tests/codeception/api/unit/validators/TotpValidatorTest.php b/tests/codeception/api/unit/validators/TotpValidatorTest.php
index fc23f9f..9385356 100644
--- a/tests/codeception/api/unit/validators/TotpValidatorTest.php
+++ b/tests/codeception/api/unit/validators/TotpValidatorTest.php
@@ -14,7 +14,7 @@ class TotpValidatorTest extends TestCase {
     public function testValidateValue() {
         $account = new Account();
         $account->otp_secret = 'some secret';
-        $controlTotp = new TOTP(null, 'some secret');
+        $controlTotp = new TOTP(null, $account->otp_secret);
 
         $validator = new TotpValidator(['account' => $account]);
 
@@ -27,9 +27,24 @@ class TotpValidatorTest extends TestCase {
         $result = $this->callProtected($validator, 'validateValue', $controlTotp->at(time() - 31));
         $this->assertEquals([E::OTP_TOKEN_INCORRECT, []], $result);
 
-        $validator->window = 60;
+        $validator->window = 2;
         $result = $this->callProtected($validator, 'validateValue', $controlTotp->at(time() - 31));
         $this->assertNull($result);
+
+        $at = time() - 400;
+        $validator->timestamp = $at;
+        $result = $this->callProtected($validator, 'validateValue', $controlTotp->now());
+        $this->assertEquals([E::OTP_TOKEN_INCORRECT, []], $result);
+
+        $result = $this->callProtected($validator, 'validateValue', $controlTotp->at($at));
+        $this->assertNull($result);
+
+        $at = function() {
+            return time() - 700;
+        };
+        $validator->timestamp = $at;
+        $result = $this->callProtected($validator, 'validateValue', $controlTotp->at($at()));
+        $this->assertNull($result);
     }
 
 }