diff --git a/dist/lively.modules-with-lively.vm.js b/dist/lively.modules-with-lively.vm.js
index 848275f..770d0b5 100644
--- a/dist/lively.modules-with-lively.vm.js
+++ b/dist/lively.modules-with-lively.vm.js
@@ -17165,8 +17165,10 @@ module.exports = function(acorn) {
     }, {
       key: "visitClassExpression",
       value: function visitClassExpression(node, scope, path) {
-        scope.classExprs.push(node);
-        scope.classExprPaths.push(path);
+        if (node.id) {
+          scope.classExprs.push(node);
+          scope.classExprPaths.push(path);
+        }
 
         var visitor = this;
         // ignore id
@@ -19361,7 +19363,7 @@ var nodes = Object.freeze({
       var stmt = parsed.body[i];
       if (topLevel.classDecls.indexOf(stmt) !== -1) {
         if (options.declarationWrapper) {
-          parsed.body.splice(i, 1, assignExpr(options.captureObj, stmt.id, funcCall(options.declarationWrapper, literal(stmt.id.name), literal("class"), stmt, options.captureObj), false));
+          parsed.body.splice(i, 1, varDecl(stmt.id, assignExpr(options.captureObj, stmt.id, funcCall(options.declarationWrapper, literal(stmt.id.name), literal("class"), stmt, options.captureObj), false), "var"));
         } else {
           parsed.body.splice(i + 1, 0, assignExpr(options.captureObj, stmt.id, stmt.id, false));
         }
@@ -19512,7 +19514,7 @@ var nodes = Object.freeze({
         body.push(stmt);
       } else {
         body = body.concat(stmt.specifiers.map(function (specifier) {
-          return topLevel.declaredNames.indexOf(specifier.local.name) > -1 ? null : varDeclOrAssignment(parsed, {
+          return lively_lang.arr.include(topLevel.declaredNames, specifier.local.name) ? null : varDeclOrAssignment(parsed, {
             type: "VariableDeclarator",
             id: specifier.local,
             init: member(options.captureObj, specifier.local)
@@ -19776,6 +19778,8 @@ var capturing = Object.freeze({
     rewriteToRegisterModuleToCaptureSetters: rewriteToRegisterModuleToCaptureSetters
   });
 
+  var defaultDeclarationWrapperName = "lively.capturing-declaration-wrapper";
+
   function evalCodeTransform(code, options) {
     // variable declaration and references in the the source code get
     // transformed so that they are bound to `varRecorderName` aren't local
@@ -19791,6 +19795,25 @@ var capturing = Object.freeze({
     // 2. capture top level vars into topLevelVarRecorder "environment"
     if (options.topLevelVarRecorder) {
 
+      // 2.1 declare a function that should wrap all definitions, i.e. all var
+      // decls, functions, classes etc that get captured will be wrapped in this
+      // function. When using this with the option.keepPreviouslyDeclaredValues
+      // we will use a wrapping function that keeps the identity of prevously
+      // defined objects
+
+      var declarationWrapperName = options.declarationWrapperName || defaultDeclarationWrapperName;
+      if (options.keepPreviouslyDeclaredValues) {
+        options.declarationWrapper = {
+          type: "MemberExpression",
+          object: { type: "Identifier", name: options.varRecorderName },
+          property: { type: "Literal", value: declarationWrapperName },
+          computed: true
+        };
+        options.topLevelVarRecorder[declarationWrapperName] = declarationWrapperForKeepingValues;
+      }
+
+      // 2.2 Here we call out to the actual code transformation that installs the
+      // capture and wrap logic
       var blacklist = (options.dontTransform || []).concat(["arguments"]),
           undeclaredToTransform = !!options.recordGlobals ? null /*all*/ : lively_lang.arr.withoutAll(Object.keys(options.topLevelVarRecorder), blacklist);
 
@@ -19833,7 +19856,39 @@ var capturing = Object.freeze({
     return result ? stringify(result) : code;
   }
 
+  function copyProperties(source, target) {
+    var exceptions = arguments.length <= 2 || arguments[2] === undefined ? [] : arguments[2];
+
+    Object.getOwnPropertyNames(source).concat(Object.getOwnPropertySymbols(source)).forEach(function (name) {
+      return exceptions.indexOf(name) === -1 && Object.defineProperty(target, name, Object.getOwnPropertyDescriptor(source, name));
+    });
+  }
+
+  function declarationWrapperForKeepingValues(name, kind, value, recorder) {
+    if (kind === "function") return value;
+
+    if (kind === "class") {
+      var existingClass = recorder[name];
+      if (typeof existingClass === "function") {
+        copyProperties(value, existingClass, ["name", "length", "prototype"]);
+        copyProperties(value.prototype, existingClass.prototype);
+        return existingClass;
+      }
+      return value;
+    }
+
+    if (!value || (typeof value === "undefined" ? "undefined" : babelHelpers.typeof(value)) !== "object" || Array.isArray(value) || value.constructor === RegExp) return value;
+
+    if (recorder.hasOwnProperty(name)) {
+      copyProperties(value, recorder[name]);
+      return recorder[name];
+    }
+
+    return value;
+  }
+
 var evalSupport = Object.freeze({
+    defaultDeclarationWrapperName: defaultDeclarationWrapperName,
     evalCodeTransform: evalCodeTransform,
     evalCodeTransformOfSystemRegisterSetters: evalCodeTransformOfSystemRegisterSetters
   });
@@ -21363,7 +21418,8 @@ var categorizer = Object.freeze({
       topLevelVarRecorder: env.recorder,
       varRecorderName: env.recorderName,
       dontTransform: env.dontTransform,
-      recordGlobals: true
+      recordGlobals: true,
+      keepPreviouslyDeclaredValues: true
     },
         isGlobal = env.recorderName === "System.global",
         header = debug ? "console.log(\"[lively.modules] executing module " + fullname + "\");\n" : "",
@@ -21500,6 +21556,7 @@ var categorizer = Object.freeze({
         debug && console.log("[lively.modules customTranslate] Installing System.register setter captures for %s", load.name);
         translated = prepareTranslatedCodeForSetterCapture(translated, load.name, env, debug);
       }
+
       debug && console.log("[lively.modules customTranslate] done %s after %sms", load.name, Date.now() - start);
       return translated;
     });
@@ -21546,7 +21603,6 @@ var categorizer = Object.freeze({
   }
 
   function instrumentSourceOfGlobalModuleLoad(System, load) {
-
     return System.translate(load).then(function (translated) {
       // return {localDeps: depNames, declare: declare};
       return { translated: translated };
@@ -23188,11 +23244,6 @@ var categorizer = Object.freeze({
   'use strict';
 
   var babelHelpers = {};
-  babelHelpers.typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) {
-    return typeof obj;
-  } : function (obj) {
-    return obj && typeof Symbol === "function" && obj.constructor === Symbol ? "symbol" : typeof obj;
-  };
 
   babelHelpers.asyncToGenerator = function (fn) {
     return function () {
@@ -23436,38 +23487,6 @@ var categorizer = Object.freeze({
   var defaultTopLevelVarRecorderName = '__lvVarRecorder';
   var startEvalFunctionName = "lively.vm-on-eval-start";
   var endEvalFunctionName = "lively.vm-on-eval-end";
-  var declarationWrapperName = "lively.vm-declaration-wrapper";
-  function copyProperties(source, target) {
-    var exceptions = arguments.length <= 2 || arguments[2] === undefined ? [] : arguments[2];
-
-    Object.getOwnPropertyNames(source).concat(Object.getOwnPropertySymbols(source)).forEach(function (name) {
-      return exceptions.indexOf(name) === -1 && Object.defineProperty(target, name, Object.getOwnPropertyDescriptor(source, name));
-    });
-  }
-
-  function declarationWrapperForKeepingValues(name, kind, value, recorder) {
-    if (kind === "function") return value;
-
-    if (kind === "class") {
-      var existingClass = recorder[name];
-      if (typeof existingClass === "function") {
-        copyProperties(value, existingClass, ["name", "length", "prototype"]);
-        copyProperties(value.prototype, existingClass.prototype);
-        return existingClass;
-      }
-      return value;
-    }
-
-    if (!value || (typeof value === "undefined" ? "undefined" : babelHelpers.typeof(value)) !== "object" || Array.isArray(value) || value.constructor === RegExp) return value;
-
-    if (recorder.hasOwnProperty(name)) {
-      copyProperties(value, recorder[name]);
-      return recorder[name];
-    }
-
-    return value;
-  }
-
   function _normalizeEvalOptions(opts) {
     if (!opts) opts = {};
     opts = Object.assign({
@@ -23506,15 +23525,6 @@ var categorizer = Object.freeze({
       };
     }
 
-    if (opts.keepPreviouslyDeclaredValues) {
-      opts.declarationWrapperFunction = declarationWrapperForKeepingValues;
-      opts.declarationWrapper = {
-        type: "MemberExpression",
-        object: { type: "Identifier", name: opts.varRecorderName },
-        property: { type: "Literal", value: declarationWrapperName },
-        computed: true
-      };
-    }
     return opts;
   }
 
@@ -23598,10 +23608,6 @@ var categorizer = Object.freeze({
       };
     }
 
-    if (options.declarationWrapperFunction) {
-      recorder[declarationWrapperName] = options.declarationWrapperFunction;
-    }
-
     // 2. Transform the code to capture top-level variables, inject function calls, ...
     try {
       code = evalCodeTransform(code, options);
@@ -23644,10 +23650,6 @@ var categorizer = Object.freeze({
       delete recorder[endEvalFunctionName];
     }
 
-    if (options.declarationWrapperFunction) {
-      delete recorder[declarationWrapperName];
-    }
-
     if (err) {
       result.isError = true;result.value = err;
     } else result.value = value;
diff --git a/dist/lively.modules.js b/dist/lively.modules.js
index e7ff54e..a0d88f5 100644
--- a/dist/lively.modules.js
+++ b/dist/lively.modules.js
@@ -17165,8 +17165,10 @@ module.exports = function(acorn) {
     }, {
       key: "visitClassExpression",
       value: function visitClassExpression(node, scope, path) {
-        scope.classExprs.push(node);
-        scope.classExprPaths.push(path);
+        if (node.id) {
+          scope.classExprs.push(node);
+          scope.classExprPaths.push(path);
+        }
 
         var visitor = this;
         // ignore id
@@ -19361,7 +19363,7 @@ var nodes = Object.freeze({
       var stmt = parsed.body[i];
       if (topLevel.classDecls.indexOf(stmt) !== -1) {
         if (options.declarationWrapper) {
-          parsed.body.splice(i, 1, assignExpr(options.captureObj, stmt.id, funcCall(options.declarationWrapper, literal(stmt.id.name), literal("class"), stmt, options.captureObj), false));
+          parsed.body.splice(i, 1, varDecl(stmt.id, assignExpr(options.captureObj, stmt.id, funcCall(options.declarationWrapper, literal(stmt.id.name), literal("class"), stmt, options.captureObj), false), "var"));
         } else {
           parsed.body.splice(i + 1, 0, assignExpr(options.captureObj, stmt.id, stmt.id, false));
         }
@@ -19512,7 +19514,7 @@ var nodes = Object.freeze({
         body.push(stmt);
       } else {
         body = body.concat(stmt.specifiers.map(function (specifier) {
-          return topLevel.declaredNames.indexOf(specifier.local.name) > -1 ? null : varDeclOrAssignment(parsed, {
+          return lively_lang.arr.include(topLevel.declaredNames, specifier.local.name) ? null : varDeclOrAssignment(parsed, {
             type: "VariableDeclarator",
             id: specifier.local,
             init: member(options.captureObj, specifier.local)
@@ -19776,6 +19778,8 @@ var capturing = Object.freeze({
     rewriteToRegisterModuleToCaptureSetters: rewriteToRegisterModuleToCaptureSetters
   });
 
+  var defaultDeclarationWrapperName = "lively.capturing-declaration-wrapper";
+
   function evalCodeTransform(code, options) {
     // variable declaration and references in the the source code get
     // transformed so that they are bound to `varRecorderName` aren't local
@@ -19791,6 +19795,25 @@ var capturing = Object.freeze({
     // 2. capture top level vars into topLevelVarRecorder "environment"
     if (options.topLevelVarRecorder) {
 
+      // 2.1 declare a function that should wrap all definitions, i.e. all var
+      // decls, functions, classes etc that get captured will be wrapped in this
+      // function. When using this with the option.keepPreviouslyDeclaredValues
+      // we will use a wrapping function that keeps the identity of prevously
+      // defined objects
+
+      var declarationWrapperName = options.declarationWrapperName || defaultDeclarationWrapperName;
+      if (options.keepPreviouslyDeclaredValues) {
+        options.declarationWrapper = {
+          type: "MemberExpression",
+          object: { type: "Identifier", name: options.varRecorderName },
+          property: { type: "Literal", value: declarationWrapperName },
+          computed: true
+        };
+        options.topLevelVarRecorder[declarationWrapperName] = declarationWrapperForKeepingValues;
+      }
+
+      // 2.2 Here we call out to the actual code transformation that installs the
+      // capture and wrap logic
       var blacklist = (options.dontTransform || []).concat(["arguments"]),
           undeclaredToTransform = !!options.recordGlobals ? null /*all*/ : lively_lang.arr.withoutAll(Object.keys(options.topLevelVarRecorder), blacklist);
 
@@ -19833,7 +19856,39 @@ var capturing = Object.freeze({
     return result ? stringify(result) : code;
   }
 
+  function copyProperties(source, target) {
+    var exceptions = arguments.length <= 2 || arguments[2] === undefined ? [] : arguments[2];
+
+    Object.getOwnPropertyNames(source).concat(Object.getOwnPropertySymbols(source)).forEach(function (name) {
+      return exceptions.indexOf(name) === -1 && Object.defineProperty(target, name, Object.getOwnPropertyDescriptor(source, name));
+    });
+  }
+
+  function declarationWrapperForKeepingValues(name, kind, value, recorder) {
+    if (kind === "function") return value;
+
+    if (kind === "class") {
+      var existingClass = recorder[name];
+      if (typeof existingClass === "function") {
+        copyProperties(value, existingClass, ["name", "length", "prototype"]);
+        copyProperties(value.prototype, existingClass.prototype);
+        return existingClass;
+      }
+      return value;
+    }
+
+    if (!value || (typeof value === "undefined" ? "undefined" : babelHelpers.typeof(value)) !== "object" || Array.isArray(value) || value.constructor === RegExp) return value;
+
+    if (recorder.hasOwnProperty(name)) {
+      copyProperties(value, recorder[name]);
+      return recorder[name];
+    }
+
+    return value;
+  }
+
 var evalSupport = Object.freeze({
+    defaultDeclarationWrapperName: defaultDeclarationWrapperName,
     evalCodeTransform: evalCodeTransform,
     evalCodeTransformOfSystemRegisterSetters: evalCodeTransformOfSystemRegisterSetters
   });
@@ -21363,7 +21418,8 @@ var categorizer = Object.freeze({
       topLevelVarRecorder: env.recorder,
       varRecorderName: env.recorderName,
       dontTransform: env.dontTransform,
-      recordGlobals: true
+      recordGlobals: true,
+      keepPreviouslyDeclaredValues: true
     },
         isGlobal = env.recorderName === "System.global",
         header = debug ? "console.log(\"[lively.modules] executing module " + fullname + "\");\n" : "",
@@ -21500,6 +21556,7 @@ var categorizer = Object.freeze({
         debug && console.log("[lively.modules customTranslate] Installing System.register setter captures for %s", load.name);
         translated = prepareTranslatedCodeForSetterCapture(translated, load.name, env, debug);
       }
+
       debug && console.log("[lively.modules customTranslate] done %s after %sms", load.name, Date.now() - start);
       return translated;
     });
@@ -21546,7 +21603,6 @@ var categorizer = Object.freeze({
   }
 
   function instrumentSourceOfGlobalModuleLoad(System, load) {
-
     return System.translate(load).then(function (translated) {
       // return {localDeps: depNames, declare: declare};
       return { translated: translated };
diff --git a/dist/lively.modules_no-deps.js b/dist/lively.modules_no-deps.js
index 4fd1097..d91580b 100644
--- a/dist/lively.modules_no-deps.js
+++ b/dist/lively.modules_no-deps.js
@@ -394,7 +394,8 @@
       topLevelVarRecorder: env.recorder,
       varRecorderName: env.recorderName,
       dontTransform: env.dontTransform,
-      recordGlobals: true
+      recordGlobals: true,
+      keepPreviouslyDeclaredValues: true
     },
         isGlobal = env.recorderName === "System.global",
         header = debug ? "console.log(\"[lively.modules] executing module " + fullname + "\");\n" : "",
@@ -531,6 +532,7 @@
         debug && console.log("[lively.modules customTranslate] Installing System.register setter captures for %s", load.name);
         translated = prepareTranslatedCodeForSetterCapture(translated, load.name, env, debug);
       }
+
       debug && console.log("[lively.modules customTranslate] done %s after %sms", load.name, Date.now() - start);
       return translated;
     });
@@ -577,7 +579,6 @@
   }
 
   function instrumentSourceOfGlobalModuleLoad(System, load) {
-
     return System.translate(load).then(function (translated) {
       // return {localDeps: depNames, declare: declare};
       return { translated: translated };
diff --git a/package.json b/package.json
index 63e83e2..384d2dd 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "lively.modules",
-  "version": "0.5.1",
+  "version": "0.5.2",
   "main": "dist/lively.modules.js",
   "repository": "https://github.com/LivelyKernel/lively.modules",
   "author": "Robert Krahn <robert.krahn@gmail.com>",
diff --git a/src/instrumentation.js b/src/instrumentation.js
index ab92000..06de282 100644
--- a/src/instrumentation.js
+++ b/src/instrumentation.js
@@ -52,7 +52,8 @@ function prepareCodeForCustomCompile(source, fullname, env, debug) {
         topLevelVarRecorder: env.recorder,
         varRecorderName: env.recorderName,
         dontTransform: env.dontTransform,
-        recordGlobals: true
+        recordGlobals: true,
+        keepPreviouslyDeclaredValues: true
       },
       isGlobal = env.recorderName === "System.global",
       header = (debug ? `console.log("[lively.modules] executing module ${fullname}");\n` : ""),
@@ -192,6 +193,7 @@ function customTranslate(proceed, load) {
       debug && console.log("[lively.modules customTranslate] Installing System.register setter captures for %s", load.name);
       translated = prepareTranslatedCodeForSetterCapture(translated, load.name, env, debug);
     }
+
     debug && console.log("[lively.modules customTranslate] done %s after %sms", load.name, Date.now()-start);
     return translated;
   });
@@ -275,7 +277,6 @@ function old_instrumentSourceOfEsmModuleLoad(System, load) {
 }
 
 function instrumentSourceOfGlobalModuleLoad(System, load) {
-
   return System.translate(load).then(translated => {
     // return {localDeps: depNames, declare: declare};
     return {translated: translated};
diff --git a/tests/changes-test.js b/tests/changes-test.js
index ca6bd46..fd25af5 100644
--- a/tests/changes-test.js
+++ b/tests/changes-test.js
@@ -164,3 +164,46 @@ describe("code changes of global format module", () => {
     expect(moduleEnv(S, module1).recorder).property("z").equal(3);
   });
 });
+
+describe("persistent definitions", () => {
+
+  var dir = System.normalizeSync("lively.modules/tests/"),
+      testProjectDir = dir + "test-project-2-dir/",
+      testProjectSpec = {
+        "file1.js": "'format esm'; class Foo { m() { return 23 }}\nvar x = {bar: 123, foo() { return this.bar + 42 }}\n",
+        "package.json": '{"name": "test-project-2", "main": "file1.js"}'
+      },
+      module1 = testProjectDir + "file1.js";
+
+  var S;
+  beforeEach(async () => {
+    S = getSystem("test", {baseURL: testProjectDir});
+    await createFiles(testProjectDir, testProjectSpec);
+  });
+
+  afterEach(async () => {
+    removeSystem("test");
+    await removeDir(testProjectDir);
+  });
+
+  it("keeps identity of class", async () => {
+    await S.import(module1);
+    var class1 = moduleEnv(S, module1).recorder.Foo;
+    expect(new class1().m()).equals(23, "Foo class not working");
+    await moduleSourceChangeAction(S, module1, s => "'format esm'; class Foo { m() { return 24 }}\n")
+    var class2 = moduleEnv(S, module1).recorder.Foo;
+    expect(new class2().m()).equals(24, "Foo class not changed");
+    expect(class1).equals(class2, "Foo class identity changed");
+  });
+
+  it("doesn't keep identity of anonymous class", async () => {
+    await S.import(module1);
+    var class1 = moduleEnv(S, module1).recorder.Foo;
+    expect(new class1().m()).equals(23, "Foo class not working");
+    await moduleSourceChangeAction(S, module1, s => "let Foo = class { m() { return 24 }}\n")
+    var class2 = moduleEnv(S, module1).recorder.Foo;
+    expect(new class2().m()).equals(24, "Foo class not changed");
+    expect(class1).not.equals(class2, "Foo class identity the same");
+  });
+
+})
\ No newline at end of file