diff --git a/src/cnako3mod.mts b/src/cnako3mod.mts
index b144b0d0..83a1284b 100755
--- a/src/cnako3mod.mts
+++ b/src/cnako3mod.mts
@@ -247,7 +247,7 @@ export class CNako3 extends NakoCompiler {
     const genOpt = new NakoGenOptions(
       isTest,
       ['plugin_node.mjs'],
-      'self.__varslist[0][\'ナデシコ種類\']=\'cnako3\';'
+      'self.__setSysVar(\'ナデシコ種類\', \'cnako3\');'
     )
     const jscode = this.compileStandalone(src, this.filename, genOpt)
     console.log(opt.output)
diff --git a/src/plugin_turtle.mjs b/src/plugin_turtle.mjs
index 75497adc..f29a750a 100644
--- a/src/plugin_turtle.mjs
+++ b/src/plugin_turtle.mjs
@@ -384,7 +384,7 @@ const PluginTurtle = {
     josi: [['に', 'へ']],
     pure: true,
     fn: function (v, sys) {
-      sys.__varslist[0]['カメ速度'] = v
+      sys.__setSysVar('カメ速度', v)
     }
   },
   'カメ移動': { // @カメの位置を[x,y]へ移動する // @かめいどう
diff --git a/src/plugin_webworker.mjs b/src/plugin_webworker.mjs
index 937c6960..b0f47dfc 100644
--- a/src/plugin_webworker.mjs
+++ b/src/plugin_webworker.mjs
@@ -298,7 +298,7 @@ const PluginWebWorker = {
         if (data.indexOf('__') === -1) {
           for (const modname of sys.__modList) {
             const varname = modname + '__' + data
-            if (typeof sys.__varslist[2][varname] !== 'undefined' || typeof sys.__varslist[1][varname] !== 'undefined') {
+            if (typeof sys.__varslist[2].get(varname) !== 'undefined' || typeof sys.__varslist[1].get(varname) !== 'undefined') {
               data = varname
               break
             }
@@ -310,14 +310,14 @@ const PluginWebWorker = {
             modNameList.push(modname)
           }
         }
-        if (typeof sys.__varslist[2][data] !== 'undefined') {
+        if (typeof sys.__varslist[2].get(data) !== 'undefined') {
           obj.push({
             type: 'val',
             name: data,
-            content: sys.__varslist[2][data]
+            content: sys.__varslist[2].get(data)
           })
         } else
-        if (typeof sys.__varslist[1][data] !== 'undefined') {
+        if (typeof sys.__varslist[1].get(data) !== 'undefined') {
           obj.push({
             type: 'func',
             name: data,
diff --git a/src/plugin_weykturtle3d.mjs b/src/plugin_weykturtle3d.mjs
index 3f072fbf..97244664 100644
--- a/src/plugin_weykturtle3d.mjs
+++ b/src/plugin_weykturtle3d.mjs
@@ -682,7 +682,7 @@ const PluginWeykTurtle3D = {
     josi: [['に', 'へ']],
     pure: true,
     fn: function (v, sys) {
-      sys.__varslist[0]['T3Dカメ速度'] = v
+      sys.__setSysVar('T3Dカメ速度', v)
     },
     return_none: true
   },
diff --git a/src/plugin_worker.mjs b/src/plugin_worker.mjs
index 88794cbc..e3380578 100644
--- a/src/plugin_worker.mjs
+++ b/src/plugin_worker.mjs
@@ -21,11 +21,11 @@ const PluginWorker = {
     pure: false,
     fn: function (func, sys) {
       func = sys.__findVar(func, null) // 文字列指定なら関数に変換
-      sys.__varslist[0]['PluginWorker:ondata'] = (data, e) => {
+      sys.__setSysVar('PluginWorker:ondata', (data, e) => {
         sys.__v0['受信データ'] = data
         sys.__v0['対象イベント'] = e
         return func(e, sys)
-      }
+      })
     },
     return_none: true
   },
diff --git a/src/wnako3webworker.mjs b/src/wnako3webworker.mjs
index 259e2b82..569a3cf3 100644
--- a/src/wnako3webworker.mjs
+++ b/src/wnako3webworker.mjs
@@ -7,10 +7,10 @@ import PluginWorker from './plugin_worker.mjs'
 class WebWorkerNakoCompiler extends NakoCompiler {
   constructor () {
     super()
-    this.__varslist[0]['ナデシコ種類'] = 'wwnako3'
-    this.__varslist[0]['PluginWorker:ondata'] = (data, event) => {
+    this.__setSysVar('ナデシコ種類', 'wwnako3')
+    this.__setSysVar('PluginWorker:ondata', (data, event) => {
       throw new Error('『NAKOワーカーデータ受信時』が呼ばれていません。')
-    }
+    })
   }
 }
 
@@ -51,9 +51,9 @@ if (typeof (navigator) === 'object' && self && self instanceof WorkerGlobalScope
           if (o.type === 'func') {
             nako3Compiler.nakoFuncList[o.name] = o.content.meta
             nako3Compiler.funclist[o.name] = o.content.func
-            nako3Compiler.__varslist[1][o.name] = () => {}
+            nako3Compiler.__varslist[1].set(o.name, () => {})
           } else if (o.type === 'val') {
-            nako3Compiler.__varslist[2][o.name] = o.content
+            nako3Compiler.__varslist[2].set(o.name, o.content)
           } else if (o.type === 'env') {
             if (o.name === 'modlist') {
               for (const modInfo of o.content) {
@@ -75,8 +75,8 @@ if (typeof (navigator) === 'object' && self && self instanceof WorkerGlobalScope
         })
         break
       case 'data':
-        if (nako3Global.__varslist[0]['PluginWorker:ondata']) {
-          nako3Global.__varslist[0]['PluginWorker:ondata'].apply(nako3Global, [value, event])
+        if (nako3Global.__getSysVar('PluginWorker:ondata')) {
+          nako3Global.__getSysVar('PluginWorker:ondata').apply(nako3Global, [value, event])
         }
         break
     }