diff --git a/rtu/modbus.lua b/rtu/modbus.lua
index ac26fc1..bb1817a 100644
--- a/rtu/modbus.lua
+++ b/rtu/modbus.lua
@@ -13,6 +13,8 @@ modbus.new = function (rtu_dev, use_parallel_read)
         use_parallel = use_parallel_read
     }
 
+    local insert = table.insert
+
     local _1_read_coils = function (c_addr_start, count)
         local tasks = {}
         local readings = {}
@@ -25,7 +27,7 @@ modbus.new = function (rtu_dev, use_parallel_read)
                 local addr = c_addr_start + i - 1
 
                 if self.use_parallel then
-                    table.insert(tasks, function ()
+                    insert(tasks, function ()
                         local reading, fault = self.rtu.read_coil(addr)
                         if fault then access_fault = true else readings[i] = reading end
                     end)
@@ -68,7 +70,7 @@ modbus.new = function (rtu_dev, use_parallel_read)
                 local addr = di_addr_start + i - 1
 
                 if self.use_parallel then
-                    table.insert(tasks, function ()
+                    insert(tasks, function ()
                         local reading, fault = self.rtu.read_di(addr)
                         if fault then access_fault = true else readings[i] = reading end
                     end)
@@ -111,7 +113,7 @@ modbus.new = function (rtu_dev, use_parallel_read)
                 local addr = hr_addr_start + i - 1
 
                 if self.use_parallel then
-                    table.insert(tasks, function ()
+                    insert(tasks, function ()
                         local reading, fault = self.rtu.read_holding_reg(addr)
                         if fault then access_fault = true else readings[i] = reading end
                     end)
@@ -154,7 +156,7 @@ modbus.new = function (rtu_dev, use_parallel_read)
                 local addr = ir_addr_start + i - 1
 
                 if self.use_parallel then
-                    table.insert(tasks, function ()
+                    insert(tasks, function ()
                         local reading, fault = self.rtu.read_input_reg(addr)
                         if fault then access_fault = true else readings[i] = reading end
                     end)
diff --git a/rtu/rtu.lua b/rtu/rtu.lua
index 9c22559..1f5c049 100644
--- a/rtu/rtu.lua
+++ b/rtu/rtu.lua
@@ -18,6 +18,8 @@ rtu.init_unit = function ()
         io_count_cache = { 0, 0, 0, 0 }
     }
 
+    local insert = table.insert
+
     local _count_io = function ()
         self.io_count_cache = { #self.discrete_inputs, #self.coils, #self.input_regs, #self.holding_regs }
     end
@@ -31,7 +33,7 @@ rtu.init_unit = function ()
 
     -- return : count of discrete inputs
     local connect_di = function (f)
-        table.insert(self.discrete_inputs, f)
+        insert(self.discrete_inputs, f)
         _count_io()
         return #self.discrete_inputs
     end
@@ -47,7 +49,7 @@ rtu.init_unit = function ()
 
     -- return : count of coils
     local connect_coil = function (f_read, f_write)
-        table.insert(self.coils, { read = f_read, write = f_write })
+        insert(self.coils, { read = f_read, write = f_write })
         _count_io()
         return #self.coils
     end
@@ -70,7 +72,7 @@ rtu.init_unit = function ()
 
     -- return : count of input registers
     local connect_input_reg = function (f)
-        table.insert(self.input_regs, f)
+        insert(self.input_regs, f)
         _count_io()
         return #self.input_regs
     end
@@ -86,7 +88,7 @@ rtu.init_unit = function ()
 
     -- return : count of holding registers
     local connect_holding_reg = function (f_read, f_write)
-        table.insert(self.holding_regs, { read = f_read, write = f_write })
+        insert(self.holding_regs, { read = f_read, write = f_write })
         _count_io()
         return #self.holding_regs
     end
@@ -293,7 +295,7 @@ rtu.comms = function (modem, local_port, server_port)
 
             if type ~= nil then
                 if type == RTU_ADVERT_TYPES.REDSTONE then
-                    table.insert(advertisement, {
+                    insert(advertisement, {
                         unit = i,
                         type = type,
                         index = units[i].index,
@@ -301,7 +303,7 @@ rtu.comms = function (modem, local_port, server_port)
                         rsio = units[i].device
                     })
                 else
-                    table.insert(advertisement, {
+                    insert(advertisement, {
                         unit = i,
                         type = type,
                         index = units[i].index,
diff --git a/scada-common/comms.lua b/scada-common/comms.lua
index f762c3b..d0e6fdf 100644
--- a/scada-common/comms.lua
+++ b/scada-common/comms.lua
@@ -4,6 +4,8 @@
 
 local comms = {}
 
+local insert = table.insert
+
 local PROTOCOLS = {
     MODBUS_TCP = 0,     -- our "MODBUS TCP"-esque protocol
     RPLC = 1,           -- reactor PLC protocol
@@ -158,7 +160,7 @@ comms.modbus_packet = function ()
         -- populate raw array
         self.raw = { self.txn_id, self.unit_id, self.func_code }
         for i = 1, self.length do
-            table.insert(self.raw, data[i])
+            insert(self.raw, data[i])
         end
     end
 
@@ -248,7 +250,7 @@ comms.rplc_packet = function ()
         -- populate raw array
         self.raw = { self.id, self.type }
         for i = 1, #data do
-            table.insert(self.raw, data[i])
+            insert(self.raw, data[i])
         end
     end
 
@@ -331,7 +333,7 @@ comms.mgmt_packet = function ()
         -- populate raw array
         self.raw = { self.type }
         for i = 1, #data do
-            table.insert(self.raw, data[i])
+            insert(self.raw, data[i])
         end
     end
 
@@ -410,7 +412,7 @@ comms.coord_packet = function ()
         -- populate raw array
         self.raw = { self.type }
         for i = 1, #data do
-            table.insert(self.raw, data[i])
+            insert(self.raw, data[i])
         end
     end
 
@@ -489,7 +491,7 @@ comms.capi_packet = function ()
         -- populate raw array
         self.raw = { self.type }
         for i = 1, #data do
-            table.insert(self.raw, data[i])
+            insert(self.raw, data[i])
         end
     end