diff --git a/src/Otp.php b/src/Otp.php
index d823753..108b0f5 100644
--- a/src/Otp.php
+++ b/src/Otp.php
@@ -56,7 +56,7 @@ public function validate(string $identifier, string $token): object
         if ($otp instanceof Model) {
             if ($otp->valid) {
                 $now = Carbon::now();
-                $validity = $otp->created_at->addMinutes($otp->validity);
+                $validity = $otp->created_at->addMinutes((int) $otp->validity);
 
                 $otp->update(['valid' => false]);