diff --git a/libraries/AP_Scripting/applets/ahrs-source-modalai-optflow.lua b/libraries/AP_Scripting/applets/ahrs-source-modalai-optflow.lua
index 1fe4c31f1c87be..fabadb9dfb05a8 100644
--- a/libraries/AP_Scripting/applets/ahrs-source-modalai-optflow.lua
+++ b/libraries/AP_Scripting/applets/ahrs-source-modalai-optflow.lua
@@ -31,18 +31,25 @@
 --         innovations are below ESRC_FLOW_THRESH
 --         rangefinder distance is below ESRC_RNGFND_MAX
 
+local PARAM_TABLE_KEY = 81
+PARAM_TABLE_PREFIX = "ESRC_"
 local MAV_SEVERITY = {EMERGENCY=0, ALERT=1, CRITICAL=2, ERROR=3, WARNING=4, NOTICE=5, INFO=6, DEBUG=7}
 
+-- bind a parameter to a variable
+function bind_param(name)
+  local p = Parameter()
+  assert(p:init(name), string.format('could not find %s parameter', name))
+  return p
+end
+
 -- add a parameter and bind it to a variable
-function bind_add_param(name, idx, default_value)
+local function bind_add_param(name, idx, default_value)
   assert(param:add_param(PARAM_TABLE_KEY, idx, name, default_value), string.format('could not add param %s', name))
-  return Parameter(PARAM_TABLE_PREFIX .. name)
+  return bind_param(PARAM_TABLE_PREFIX .. name)
 end
 
--- param table
-local PARAM_TABLE_KEY = 81
-PARAM_TABLE_PREFIX = "ESCR_"
-assert(param:add_table(PARAM_TABLE_KEY, PARAM_TABLE_PREFIX, 6), 'ahrs-source-modalai-optflow: could not add param table')
+-- add param table
+assert(param:add_table(PARAM_TABLE_KEY, PARAM_TABLE_PREFIX, 5), 'ahrs-source-modalai-optflow: could not add param table')
 
 --[[
   // @Param: ESRC_EXTN_THRESH
@@ -227,7 +234,6 @@ function update()
     end
     play_source_tune(source_prev)
   end
-  end
 
   -- auto switching
   if auto_switch and (auto_source >= 0) and (auto_source ~= source_prev) then