diff --git a/supervisor/session/rtu/boiler.lua b/supervisor/session/rtu/boiler.lua
index 78931ec..320d7e4 100644
--- a/supervisor/session/rtu/boiler.lua
+++ b/supervisor/session/rtu/boiler.lua
@@ -7,6 +7,7 @@ local txnctrl = require("supervisor.session.rtu.txnctrl")
 local boiler = {}
 
 local PROTOCOLS = comms.PROTOCOLS
+local RTU_UNIT_TYPES = comms.RTU_UNIT_TYPES
 local MODBUS_FCODE = types.MODBUS_FCODE
 
 local rtu_t = types.rtu_t
@@ -29,7 +30,7 @@ local PERIODICS = {
 ---@param out_queue mqueue
 boiler.new = function (session_id, advert, out_queue)
     -- type check
-    if advert.type ~= rtu_t.boiler then
+    if advert.type ~= RTU_UNIT_TYPES.BOILER then
         log.error("attempt to instantiate boiler RTU for type '" .. advert.type .. "'. this is a bug.")
         return nil
     end
diff --git a/supervisor/session/rtu/emachine.lua b/supervisor/session/rtu/emachine.lua
index b6c89b6..9428806 100644
--- a/supervisor/session/rtu/emachine.lua
+++ b/supervisor/session/rtu/emachine.lua
@@ -7,6 +7,7 @@ local txnctrl = require("supervisor.session.rtu.txnctrl")
 local emachine = {}
 
 local PROTOCOLS = comms.PROTOCOLS
+local RTU_UNIT_TYPES = comms.RTU_UNIT_TYPES
 local MODBUS_FCODE = types.MODBUS_FCODE
 
 local rtu_t = types.rtu_t
@@ -27,7 +28,7 @@ local PERIODICS = {
 ---@param out_queue mqueue
 emachine.new = function (session_id, advert, out_queue)
     -- type check
-    if advert.type ~= rtu_t.energy_machine then
+    if advert.type ~= RTU_UNIT_TYPES.EMACHINE then
         log.error("attempt to instantiate emachine RTU for type '" .. advert.type .. "'. this is a bug.")
         return nil
     end
diff --git a/supervisor/session/rtu/turbine.lua b/supervisor/session/rtu/turbine.lua
index ccca068..66429f3 100644
--- a/supervisor/session/rtu/turbine.lua
+++ b/supervisor/session/rtu/turbine.lua
@@ -7,6 +7,7 @@ local txnctrl = require("supervisor.session.rtu.txnctrl")
 local turbine = {}
 
 local PROTOCOLS = comms.PROTOCOLS
+local RTU_UNIT_TYPES = comms.RTU_UNIT_TYPES
 local DUMPING_MODE = types.DUMPING_MODE
 local MODBUS_FCODE = types.MODBUS_FCODE
 
@@ -30,7 +31,7 @@ local PERIODICS = {
 ---@param out_queue mqueue
 turbine.new = function (session_id, advert, out_queue)
     -- type check
-    if advert.type ~= rtu_t.turbine then
+    if advert.type ~= RTU_UNIT_TYPES.TURBINE then
         log.error("attempt to instantiate turbine RTU for type '" .. advert.type .. "'. this is a bug.")
         return nil
     end