diff --git a/packages/babel-helper-create-class-features-plugin/src/fields.ts b/packages/babel-helper-create-class-features-plugin/src/fields.ts
index 790a941ca913..39885e15b2c6 100644
--- a/packages/babel-helper-create-class-features-plugin/src/fields.ts
+++ b/packages/babel-helper-create-class-features-plugin/src/fields.ts
@@ -206,6 +206,24 @@ function unshadow(
   }
 }
 
+export function buildCheckInRHS(
+  rhs: t.Expression,
+  file: File,
+  inRHSIsObject?: boolean,
+) {
+  let helperRef;
+  try {
+    helperRef = file.addHelper("checkInRHS");
+  } catch (err) {
+    if (err.code !== "BABEL_HELPER_UNKNOWN") {
+      throw err;
+    }
+  }
+  return helperRef !== undefined && inRHSIsObject !== true
+    ? t.callExpression(helperRef, [rhs])
+    : rhs;
+}
+
 const privateInVisitor = privateNameVisitorFactory<{
   classRef: t.Identifier;
   file: File;
@@ -230,9 +248,10 @@ const privateInVisitor = privateNameVisitorFactory<{
     if (privateFieldsAsProperties) {
       const { id } = privateNamesMap.get(name);
       path.replaceWith(template.expression.ast`
-        Object.prototype.hasOwnProperty.call(${file.addHelper(
-          "checkInRHS",
-        )}(${right}), ${t.cloneNode(id)})
+        Object.prototype.hasOwnProperty.call(${buildCheckInRHS(
+          right,
+          file,
+        )}, ${t.cloneNode(id)})
       `);
       return;
     }
@@ -241,17 +260,19 @@ const privateInVisitor = privateNameVisitorFactory<{
 
     if (isStatic) {
       path.replaceWith(
-        template.expression.ast`${file.addHelper(
-          "checkInRHS",
-        )}(${right}) === ${t.cloneNode(this.classRef)}`,
+        template.expression.ast`${buildCheckInRHS(
+          right,
+          file,
+        )} === ${t.cloneNode(this.classRef)}`,
       );
       return;
     }
 
     path.replaceWith(
-      template.expression.ast`${t.cloneNode(id)}.has(${file.addHelper(
-        "checkInRHS",
-      )}(${right}))`,
+      template.expression.ast`${t.cloneNode(id)}.has(${buildCheckInRHS(
+        right,
+        file,
+      )})`,
     );
   },
 });
diff --git a/packages/babel-helper-create-class-features-plugin/src/index.ts b/packages/babel-helper-create-class-features-plugin/src/index.ts
index 6705416de160..4a655f30ff1a 100644
--- a/packages/babel-helper-create-class-features-plugin/src/index.ts
+++ b/packages/babel-helper-create-class-features-plugin/src/index.ts
@@ -8,6 +8,7 @@ import {
   buildPrivateNamesMap,
   transformPrivateNamesUsage,
   buildFieldsInitNodes,
+  buildCheckInRHS,
 } from "./fields";
 import type { PropPath } from "./fields";
 import { buildDecoratedClass, hasDecorators } from "./decorators";
@@ -15,7 +16,7 @@ import { injectInitialization, extractComputedKeys } from "./misc";
 import { enableFeature, FEATURES, isLoose, shouldTransform } from "./features";
 import { assertFieldTransformed } from "./typescript";
 
-export { FEATURES, enableFeature, injectInitialization };
+export { FEATURES, enableFeature, injectInitialization, buildCheckInRHS };
 
 declare const PACKAGE_JSON: { name: string; version: string };
 
diff --git a/packages/babel-plugin-proposal-private-property-in-object/src/index.ts b/packages/babel-plugin-proposal-private-property-in-object/src/index.ts
index 0266b990e4e8..91ff58cd94a7 100644
--- a/packages/babel-plugin-proposal-private-property-in-object/src/index.ts
+++ b/packages/babel-plugin-proposal-private-property-in-object/src/index.ts
@@ -4,6 +4,7 @@ import {
   enableFeature,
   FEATURES,
   injectInitialization as injectConstructorInit,
+  buildCheckInRHS,
 } from "@babel/helper-create-class-features-plugin";
 import annotateAsPure from "@babel/helper-annotate-as-pure";
 import type * as t from "@babel/types";
@@ -121,6 +122,7 @@ export default declare((api, opt: Options) => {
     visitor: {
       BinaryExpression(path, state) {
         const { node } = path;
+        const { file } = state;
         if (node.operator !== "in") return;
         if (!t.isPrivateName(node.left)) return;
 
@@ -158,9 +160,10 @@ export default declare((api, opt: Options) => {
             }
             path.replaceWith(
               template.expression.ast`
-                ${t.cloneNode(outerClass.node.id)} === ${state.addHelper(
-                "checkInRHS",
-              )}(${node.right})
+                ${t.cloneNode(outerClass.node.id)} === ${buildCheckInRHS(
+                node.right,
+                file,
+              )}
               `,
             );
           } else {
@@ -173,9 +176,10 @@ export default declare((api, opt: Options) => {
             );
 
             path.replaceWith(
-              template.expression.ast`${id}.has(${state.addHelper(
-                "checkInRHS",
-              )}(${node.right}))`,
+              template.expression.ast`${id}.has(${buildCheckInRHS(
+                node.right,
+                file,
+              )})`,
             );
           }
         } else {
@@ -191,9 +195,10 @@ export default declare((api, opt: Options) => {
           );
 
           path.replaceWith(
-            template.expression.ast`${id}.has(${state.addHelper(
-              "checkInRHS",
-            )}(${node.right}))`,
+            template.expression.ast`${id}.has(${buildCheckInRHS(
+              node.right,
+              file,
+            )})`,
           );
         }
       },