diff --git a/source/MAC/IEEE802_15_4/mac_mcps_sap.c b/source/MAC/IEEE802_15_4/mac_mcps_sap.c
index 7c87456621b..8a28c4e93a2 100644
--- a/source/MAC/IEEE802_15_4/mac_mcps_sap.c
+++ b/source/MAC/IEEE802_15_4/mac_mcps_sap.c
@@ -1286,14 +1286,8 @@ static bool mac_frame_security_parameters_init(ccm_globals_t *ccm_ptr, protocol_
         if (buffer->fcf_dsn.DstAddrMode && buffer->fcf_dsn.ackRequested) {
             device_description =  mac_sec_mib_device_description_get(rf_ptr, buffer->DstAddr, buffer->fcf_dsn.DstAddrMode);
             if (!device_description) {
-
-                if (rf_ptr->mac_security_bypass_unknow_device && (buffer->fcf_dsn.SrcAddrMode == MAC_ADDR_MODE_64_BIT
-                        && buffer->aux_header.securityLevel > AES_SECURITY_LEVEL_ENC)) {
-
-                } else {
-                    buffer->status = MLME_UNAVAILABLE_KEY;
-                    return false;
-                }
+                buffer->status = MLME_UNAVAILABLE_KEY;
+                return false;
             }
         }
         nonce_ext_64_ptr = rf_ptr->mac64;