diff --git a/platform/mellanox/mlnx-platform-api/sonic_platform/chassis.py b/platform/mellanox/mlnx-platform-api/sonic_platform/chassis.py
index af58886ca10..e1efe211c76 100644
--- a/platform/mellanox/mlnx-platform-api/sonic_platform/chassis.py
+++ b/platform/mellanox/mlnx-platform-api/sonic_platform/chassis.py
@@ -1104,6 +1104,7 @@ def _verify_reboot_cause(self, filename):
     def initialize_reboot_cause(self):
         self.reboot_major_cause_dict = {
             'reset_main_pwr_fail'       :   self.REBOOT_CAUSE_POWER_LOSS,
+            'reset_ac_pwr_fail'         :   self.REBOOT_CAUSE_POWER_LOSS,
             'reset_aux_pwr_or_ref'      :   self.REBOOT_CAUSE_POWER_LOSS,
             'reset_aux_pwr_or_reload'   :   self.REBOOT_CAUSE_POWER_LOSS,
             'reset_aux_pwr_or_fu'       :   self.REBOOT_CAUSE_POWER_LOSS,