diff --git a/packages/near-membrane-shared/src/Function.ts b/packages/near-membrane-shared/src/Function.ts
index 1326555c..e18ab8c8 100644
--- a/packages/near-membrane-shared/src/Function.ts
+++ b/packages/near-membrane-shared/src/Function.ts
@@ -26,6 +26,18 @@ export function noop() {
     // No operation performed.
 }
 
+export function isProxyMaskedFunction(value: any): boolean {
+    // To extract the flag value of a blue near-membrane proxy we must perform
+    // a two step handshake. First, we trigger the "has" trap for the
+    // `LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL` property which must report
+    // `false`. Second, we trigger the "get" trap to return the flag value.
+    return (
+        typeof value === 'function' &&
+        !(LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL in value) &&
+        (value as any)[LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL] === true
+    );
+}
+
 export function proxyMaskFunction<T extends Function>(
     func: Function,
     maskFunc: T,
diff --git a/packages/near-membrane-shared/src/NearMembrane.ts b/packages/near-membrane-shared/src/NearMembrane.ts
index bb8029d7..6cd24f1d 100644
--- a/packages/near-membrane-shared/src/NearMembrane.ts
+++ b/packages/near-membrane-shared/src/NearMembrane.ts
@@ -1,5 +1,4 @@
 import {
-    LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL,
     LOCKER_NEAR_MEMBRANE_SERIALIZED_VALUE_SYMBOL,
     LOCKER_NEAR_MEMBRANE_SYMBOL,
 } from './constants';
@@ -32,15 +31,3 @@ export function isNearMembraneProxy(value: any): boolean {
     }
     return false;
 }
-
-export function isNearMembraneProxyMaskedFunction(value: any): boolean {
-    // To extract the flag value of a blue near-membrane proxy we must perform
-    // a two step handshake. First, we trigger the "has" trap for the
-    // `LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL` property which must report
-    // `false`. Second, we trigger the "get" trap to return the flag value.
-    return (
-        typeof value === 'function' &&
-        !(LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL in value) &&
-        (value as any)[LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL] === true
-    );
-}
diff --git a/packages/near-membrane-shared/src/__tests__/Function.spec.js b/packages/near-membrane-shared/src/__tests__/Function.spec.js
index 40735af8..5577171c 100644
--- a/packages/near-membrane-shared/src/__tests__/Function.spec.js
+++ b/packages/near-membrane-shared/src/__tests__/Function.spec.js
@@ -1,11 +1,25 @@
 import {
     ERR_ILLEGAL_PROPERTY_ACCESS,
+    isProxyMaskedFunction,
     LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL,
     noop,
     proxyMaskFunction,
 } from '../../dist/index.mjs.js';
 
 describe('Function', () => {
+    it('isProxyMaskedFunction', () => {
+        expect(isProxyMaskedFunction({})).toBe(false);
+        expect(isProxyMaskedFunction(null)).toBe(false);
+        expect(isProxyMaskedFunction(undefined)).toBe(false);
+        const func = () => 'func';
+        func[LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL] = true;
+        expect(isProxyMaskedFunction(func)).toBe(false);
+        const mask = () => 'mask';
+        expect(isProxyMaskedFunction(mask)).toBe(false);
+        const masked = proxyMaskFunction(func, mask);
+        expect(isProxyMaskedFunction(masked)).toBe(true);
+    });
+
     it('noop', () => {
         expect(noop()).toBe(undefined);
         expect(noop(null)).toBe(undefined);
diff --git a/packages/near-membrane-shared/src/__tests__/NearMembrane.spec.js b/packages/near-membrane-shared/src/__tests__/NearMembrane.spec.js
index aa823b7b..3574a5c4 100644
--- a/packages/near-membrane-shared/src/__tests__/NearMembrane.spec.js
+++ b/packages/near-membrane-shared/src/__tests__/NearMembrane.spec.js
@@ -1,11 +1,8 @@
 import {
     getNearMembraneProxySerializedValue,
     isNearMembraneProxy,
-    isNearMembraneProxyMaskedFunction,
-    LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL,
     LOCKER_NEAR_MEMBRANE_SERIALIZED_VALUE_SYMBOL,
     LOCKER_NEAR_MEMBRANE_SYMBOL,
-    proxyMaskFunction,
 } from '../../dist/index.mjs.js';
 
 describe('NearMembrane', () => {
@@ -30,17 +27,4 @@ describe('NearMembrane', () => {
             })
         ).toBe(false);
     });
-
-    it('isNearMembraneProxyMaskedFunction', () => {
-        expect(isNearMembraneProxyMaskedFunction({})).toBe(false);
-        expect(isNearMembraneProxyMaskedFunction(null)).toBe(false);
-        expect(isNearMembraneProxyMaskedFunction(undefined)).toBe(false);
-        const func = () => 'func';
-        func[LOCKER_NEAR_MEMBRANE_PROXY_MASKED_SYMBOL] = true;
-        expect(isNearMembraneProxyMaskedFunction(func)).toBe(false);
-        const mask = () => 'mask';
-        expect(isNearMembraneProxyMaskedFunction(mask)).toBe(false);
-        const masked = proxyMaskFunction(func, mask);
-        expect(isNearMembraneProxyMaskedFunction(masked)).toBe(true);
-    });
 });
diff --git a/test/membrane/date.spec.js b/test/membrane/date.spec.js
index 49935373..75c7a0a1 100644
--- a/test/membrane/date.spec.js
+++ b/test/membrane/date.spec.js
@@ -1,4 +1,4 @@
-import { isNearMembraneProxyMaskedFunction } from '@locker/near-membrane-shared';
+import { isProxyMaskedFunction } from '@locker/near-membrane-shared';
 import createVirtualEnvironment from '@locker/near-membrane-dom';
 
 describe('Date', () => {
@@ -11,7 +11,7 @@ describe('Date', () => {
         env.evaluate(`
             expect(Date.prototype.toJSON.toString()).toContain('[native code]');
         `);
-        expect(isNearMembraneProxyMaskedFunction(Date.prototype.toJSON)).toBe(false);
+        expect(isProxyMaskedFunction(Date.prototype.toJSON)).toBe(false);
     });
 
     it('Date.prototype.toJSON does not support proxy masked symbol handshake', () => {
diff --git a/test/membrane/json.spec.js b/test/membrane/json.spec.js
index a3144d7c..a5548724 100644
--- a/test/membrane/json.spec.js
+++ b/test/membrane/json.spec.js
@@ -1,4 +1,4 @@
-import { isNearMembraneProxyMaskedFunction } from '@locker/near-membrane-shared';
+import { isProxyMaskedFunction } from '@locker/near-membrane-shared';
 import createVirtualEnvironment from '@locker/near-membrane-dom';
 
 describe('JSON', () => {
@@ -11,7 +11,7 @@ describe('JSON', () => {
         env.evaluate(`
             expect(JSON.stringify.toString()).toContain('[native code]');
         `);
-        expect(isNearMembraneProxyMaskedFunction(JSON.stringify)).toBe(false);
+        expect(isProxyMaskedFunction(JSON.stringify)).toBe(false);
     });
 
     it('JSON.stringify does not support proxy masked symbol handshake', () => {