diff --git a/packages/babel-helper-create-class-features-plugin/src/fields.js b/packages/babel-helper-create-class-features-plugin/src/fields.js
index e14b7b1a5ac5..519dfeba7227 100644
--- a/packages/babel-helper-create-class-features-plugin/src/fields.js
+++ b/packages/babel-helper-create-class-features-plugin/src/fields.js
@@ -319,8 +319,8 @@ function buildPrivateStaticFieldInitSpec(prop, privateNamesMap) {
         // configurable is false by default
         // enumerable is false by default
         // writable is false by default
-        get: ${getId ? getId.name : "null"},
-        set: ${setId ? setId.name : "null"}
+        get: ${getId ? getId.name : prop.scope.buildUndefinedNode()},
+        set: ${setId ? setId.name : prop.scope.buildUndefinedNode()}
       }
     `;
   }
@@ -363,8 +363,8 @@ function buildPrivateMethodInitLoose(ref, prop, privateNamesMap) {
         // configurable is false by default
         // enumerable is false by default
         // writable is false by default
-        get: ${getId ? getId.name : "undefined"},
-        set: ${setId ? setId.name : "undefined"}
+        get: ${getId ? getId.name : prop.scope.buildUndefinedNode()},
+        set: ${setId ? setId.name : prop.scope.buildUndefinedNode()}
       });
     `;
   }
@@ -383,8 +383,8 @@ function buildPrivateInstanceMethodInitSpec(ref, prop, privateNamesMap) {
 
     return template.statement.ast`
       ${id}.set(${ref}, {
-        get: ${getId ? getId.name : "undefined"},
-        set: ${setId ? setId.name : "undefined"}
+        get: ${getId ? getId.name : prop.scope.buildUndefinedNode()},
+        set: ${setId ? setId.name : prop.scope.buildUndefinedNode()}
       });
     `;
   }
@@ -433,8 +433,8 @@ function buildPrivateStaticMethodInitLoose(ref, prop, state, privateNamesMap) {
         // configurable is false by default
         // enumerable is false by default
         // writable is false by default
-        get: ${getId ? getId.name : "undefined"},
-        set: ${setId ? setId.name : "undefined"}
+        get: ${getId ? getId.name : prop.scope.buildUndefinedNode()},
+        set: ${setId ? setId.name : prop.scope.buildUndefinedNode()}
       })
     `;
   }
diff --git a/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/get-only-setter/output.js b/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/get-only-setter/output.js
index cdd5951ff669..9d7d52b847b8 100644
--- a/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/get-only-setter/output.js
+++ b/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/get-only-setter/output.js
@@ -1,7 +1,7 @@
 class Cl {
   constructor() {
     Object.defineProperty(this, _privateFieldValue, {
-      get: undefined,
+      get: void 0,
       set: _set_privateFieldValue
     });
     Object.defineProperty(this, _privateField, {
diff --git a/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/set-only-getter/output.js b/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/set-only-getter/output.js
index dd0746627f39..eb046676cf54 100644
--- a/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/set-only-getter/output.js
+++ b/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors-loose/set-only-getter/output.js
@@ -2,7 +2,7 @@ class Cl {
   constructor() {
     Object.defineProperty(this, _privateFieldValue, {
       get: _get_privateFieldValue,
-      set: undefined
+      set: void 0
     });
     Object.defineProperty(this, _privateField, {
       writable: true,
diff --git a/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/get-only-setter/output.js b/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/get-only-setter/output.js
index cee46af765f3..15691ee34a50 100644
--- a/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/get-only-setter/output.js
+++ b/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/get-only-setter/output.js
@@ -1,7 +1,7 @@
 class Cl {
   constructor() {
     _privateFieldValue.set(this, {
-      get: undefined,
+      get: void 0,
       set: _set_privateFieldValue
     });
 
diff --git a/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/set-only-getter/output.js b/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/set-only-getter/output.js
index f332457f800e..e301c07805de 100644
--- a/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/set-only-getter/output.js
+++ b/packages/babel-plugin-proposal-private-methods/test/fixtures/accessors/set-only-getter/output.js
@@ -2,7 +2,7 @@ class Cl {
   constructor() {
     _privateFieldValue.set(this, {
       get: _get_privateFieldValue,
-      set: undefined
+      set: void 0
     });
 
     _privateField.set(this, {
diff --git a/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors-loose/get-only-setter/output.js b/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors-loose/get-only-setter/output.js
index 16d8f5442ddc..adb85a9ead8c 100644
--- a/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors-loose/get-only-setter/output.js
+++ b/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors-loose/get-only-setter/output.js
@@ -18,6 +18,6 @@ Object.defineProperty(Cl, _PRIVATE_STATIC_FIELD, {
   value: 0
 });
 Object.defineProperty(Cl, _privateStaticFieldValue, {
-  get: undefined,
+  get: void 0,
   set: _set_privateStaticFieldValue
 });
diff --git a/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors-loose/set-only-getter/output.js b/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors-loose/set-only-getter/output.js
index 5d570a8fafb9..73e658037394 100644
--- a/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors-loose/set-only-getter/output.js
+++ b/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors-loose/set-only-getter/output.js
@@ -19,5 +19,5 @@ Object.defineProperty(Cl, _PRIVATE_STATIC_FIELD, {
 });
 Object.defineProperty(Cl, _privateStaticFieldValue, {
   get: _get_privateStaticFieldValue,
-  set: undefined
+  set: void 0
 });
diff --git a/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors/get-only-setter/output.js b/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors/get-only-setter/output.js
index aff5135c8ed5..31c1bf46873e 100644
--- a/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors/get-only-setter/output.js
+++ b/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors/get-only-setter/output.js
@@ -14,6 +14,6 @@ var _PRIVATE_STATIC_FIELD = {
   value: 0
 };
 var _privateStaticFieldValue = {
-  get: null,
+  get: void 0,
   set: _set_privateStaticFieldValue
 };
diff --git a/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors/set-only-getter/output.js b/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors/set-only-getter/output.js
index b58651007e0d..fa3aebd45bfc 100644
--- a/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors/set-only-getter/output.js
+++ b/packages/babel-plugin-proposal-private-methods/test/fixtures/static-accessors/set-only-getter/output.js
@@ -15,5 +15,5 @@ var _PRIVATE_STATIC_FIELD = {
 };
 var _privateStaticFieldValue = {
   get: _get_privateStaticFieldValue,
-  set: null
+  set: void 0
 };