diff --git a/packages/relay-experimental/ExecutionEnvironment.js b/packages/relay-experimental/ExecutionEnvironment.js
new file mode 100644
index 0000000000000..67d9e14974f39
--- /dev/null
+++ b/packages/relay-experimental/ExecutionEnvironment.js
@@ -0,0 +1,20 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @emails oncall+relay
+ * @flow strict-local
+ * @format
+ */
+
+// flowlint ambiguous-object-type:error
+
+'use strict';
+
+const ExecutionEnvironment = {
+  isServer: typeof window === 'undefined',
+};
+
+module.exports = ExecutionEnvironment;
diff --git a/packages/relay-experimental/QueryResource.js b/packages/relay-experimental/QueryResource.js
index 7a162565079a6..2857c1af76e30 100644
--- a/packages/relay-experimental/QueryResource.js
+++ b/packages/relay-experimental/QueryResource.js
@@ -13,7 +13,7 @@
 
 'use strict';
 
-const ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
+const ExecutionEnvironment = require('./ExecutionEnvironment');
 const LRUCache = require('./LRUCache');
 
 const invariant = require('invariant');
@@ -152,7 +152,7 @@ function createCacheEntry(
     temporaryRetain(environment: IEnvironment): Disposable {
       // NOTE: If we're executing in a server environment, there's no need
       // to create temporary retains, since the component will never commit.
-      if (!ExecutionEnvironment.canUseDOM) {
+      if (ExecutionEnvironment.isServer) {
         return {dispose: () => {}};
       }
 
diff --git a/packages/relay-experimental/__tests__/EntryPointContainer-test.js b/packages/relay-experimental/__tests__/EntryPointContainer-test.js
index 0f296fe0fdf6d..37b7ba9d66971 100644
--- a/packages/relay-experimental/__tests__/EntryPointContainer-test.js
+++ b/packages/relay-experimental/__tests__/EntryPointContainer-test.js
@@ -13,8 +13,8 @@
 
 'use strict';
 
-jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-  canUseDOM: true,
+jest.mock('../ExecutionEnvironment', () => ({
+  isServer: false,
 }));
 
 const EntryPointContainer = require('../EntryPointContainer.react');
diff --git a/packages/relay-experimental/__tests__/LazyLoadEntryPointContainer_DEEPRECATED-test.js b/packages/relay-experimental/__tests__/LazyLoadEntryPointContainer_DEEPRECATED-test.js
index 934a421ee7de1..e55fa6b09c6dd 100644
--- a/packages/relay-experimental/__tests__/LazyLoadEntryPointContainer_DEEPRECATED-test.js
+++ b/packages/relay-experimental/__tests__/LazyLoadEntryPointContainer_DEEPRECATED-test.js
@@ -13,8 +13,8 @@
 
 'use strict';
 
-jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-  canUseDOM: true,
+jest.mock('../ExecutionEnvironment', () => ({
+  isServer: false,
 }));
 
 const LazyLoadEntryPointContainer_DEPRECATED = require('../LazyLoadEntryPointContainer_DEPRECATED.react');
diff --git a/packages/relay-experimental/__tests__/QueryResource-test.js b/packages/relay-experimental/__tests__/QueryResource-test.js
index ab51dca68b29f..95513f79745f0 100644
--- a/packages/relay-experimental/__tests__/QueryResource-test.js
+++ b/packages/relay-experimental/__tests__/QueryResource-test.js
@@ -47,8 +47,8 @@ describe('QueryResource', () => {
   };
 
   beforeEach(() => {
-    jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-      canUseDOM: () => true,
+    jest.mock('../ExecutionEnvironment', () => ({
+      isServer: false,
     }));
     store = new Store(new RecordSource());
     environment = createMockEnvironment({store});
diff --git a/packages/relay-experimental/__tests__/fetchQuery-test.js b/packages/relay-experimental/__tests__/fetchQuery-test.js
index 677a6f22d94f3..90fed9ed8f760 100644
--- a/packages/relay-experimental/__tests__/fetchQuery-test.js
+++ b/packages/relay-experimental/__tests__/fetchQuery-test.js
@@ -36,8 +36,8 @@ describe('fetchQuery', () => {
   let retained = [];
   beforeEach(() => {
     retained = [];
-    jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-      canUseDOM: () => true,
+    jest.mock('../ExecutionEnvironment', () => ({
+      isServer: false,
     }));
     environment = createMockEnvironment();
     environment.retain.mockImplementation(obj => {
diff --git a/packages/relay-experimental/__tests__/preloadQuery_DEPRECATED-test.js b/packages/relay-experimental/__tests__/preloadQuery_DEPRECATED-test.js
index 5572597df0962..cf69bf612324d 100644
--- a/packages/relay-experimental/__tests__/preloadQuery_DEPRECATED-test.js
+++ b/packages/relay-experimental/__tests__/preloadQuery_DEPRECATED-test.js
@@ -13,8 +13,8 @@
 
 'use strict';
 
-jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-  canUseDOM: true,
+jest.mock('../ExecutionEnvironment', () => ({
+  isServer: false,
 }));
 
 const preloadQuery_DEPRECATED = require('../preloadQuery_DEPRECATED');
diff --git a/packages/relay-experimental/__tests__/prepareEntryPoint-test.js b/packages/relay-experimental/__tests__/prepareEntryPoint-test.js
index 31498dfd37158..f53194899fd10 100644
--- a/packages/relay-experimental/__tests__/prepareEntryPoint-test.js
+++ b/packages/relay-experimental/__tests__/prepareEntryPoint-test.js
@@ -13,8 +13,8 @@
 
 'use strict';
 
-jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-  canUseDOM: true,
+jest.mock('../ExecutionEnvironment', () => ({
+  isServer: false,
 }));
 
 const prepareEntryPoint = require('../prepareEntryPoint');
diff --git a/packages/relay-experimental/__tests__/useBlockingPaginationFragment-test.js b/packages/relay-experimental/__tests__/useBlockingPaginationFragment-test.js
index 38dc987329540..72385ddd29d38 100644
--- a/packages/relay-experimental/__tests__/useBlockingPaginationFragment-test.js
+++ b/packages/relay-experimental/__tests__/useBlockingPaginationFragment-test.js
@@ -130,8 +130,8 @@ describe('useBlockingPaginationFragment', () => {
     jest.resetModules();
     jest.spyOn(console, 'warn').mockImplementationOnce(() => {});
     jest.mock('warning');
-    jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-      canUseDOM: () => true,
+    jest.mock('../ExecutionEnvironment', () => ({
+      isServer: false,
     }));
     renderSpy = jest.fn();
 
diff --git a/packages/relay-experimental/__tests__/useBlockingPaginationFragment-with-suspense-transition-test.js b/packages/relay-experimental/__tests__/useBlockingPaginationFragment-with-suspense-transition-test.js
index 9ca8e9bea8340..b54b6ee2b9231 100644
--- a/packages/relay-experimental/__tests__/useBlockingPaginationFragment-with-suspense-transition-test.js
+++ b/packages/relay-experimental/__tests__/useBlockingPaginationFragment-with-suspense-transition-test.js
@@ -173,8 +173,8 @@ describe('useBlockingPaginationFragment with useSuspenseTransition', () => {
       jest.resetModules();
       jest.spyOn(console, 'warn').mockImplementationOnce(() => {});
       jest.mock('warning');
-      jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-        canUseDOM: () => true,
+      jest.mock('../ExecutionEnvironment', () => ({
+        isServer: false,
       }));
       renderSpy = jest.fn();
 
diff --git a/packages/relay-experimental/__tests__/useFragmentNode-test.js b/packages/relay-experimental/__tests__/useFragmentNode-test.js
index 37199c332ac78..88cb3ed5e02e2 100644
--- a/packages/relay-experimental/__tests__/useFragmentNode-test.js
+++ b/packages/relay-experimental/__tests__/useFragmentNode-test.js
@@ -137,8 +137,8 @@ beforeEach(() => {
   jest.mock('scheduler', () => {
     return jest.requireActual('scheduler/unstable_mock');
   });
-  jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-    canUseDOM: () => true,
+  jest.mock('../ExecutionEnvironment', () => ({
+    isServer: false,
   }));
   renderSpy = jest.fn();
 
diff --git a/packages/relay-experimental/__tests__/useLazyLoadQueryNode-test.js b/packages/relay-experimental/__tests__/useLazyLoadQueryNode-test.js
index 96e7c0d5a8341..a2566738217ab 100644
--- a/packages/relay-experimental/__tests__/useLazyLoadQueryNode-test.js
+++ b/packages/relay-experimental/__tests__/useLazyLoadQueryNode-test.js
@@ -68,8 +68,8 @@ describe('useLazyLoadQueryNode', () => {
   beforeEach(() => {
     jest.resetModules();
     jest.spyOn(console, 'warn').mockImplementationOnce(() => {});
-    jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-      canUseDOM: () => true,
+    jest.mock('../ExecutionEnvironment', () => ({
+      isServer: false,
     }));
 
     ({
diff --git a/packages/relay-experimental/__tests__/useLegacyPaginationFragment-test.js b/packages/relay-experimental/__tests__/useLegacyPaginationFragment-test.js
index 07adcd6859e9b..4db3730ae4a47 100644
--- a/packages/relay-experimental/__tests__/useLegacyPaginationFragment-test.js
+++ b/packages/relay-experimental/__tests__/useLegacyPaginationFragment-test.js
@@ -663,8 +663,8 @@ describe('useLegacyPaginationFragment', () => {
 
     beforeEach(() => {
       jest.resetModules();
-      jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-        canUseDOM: () => true,
+      jest.mock('../ExecutionEnvironment', () => ({
+        isServer: false,
       }));
       jest.doMock('scheduler', () => {
         const original = jest.requireActual('scheduler/unstable_mock');
diff --git a/packages/relay-experimental/__tests__/usePreloadedQuery-test.js b/packages/relay-experimental/__tests__/usePreloadedQuery-test.js
index a5ba047cbd367..b1372dd5093bd 100644
--- a/packages/relay-experimental/__tests__/usePreloadedQuery-test.js
+++ b/packages/relay-experimental/__tests__/usePreloadedQuery-test.js
@@ -13,8 +13,8 @@
 
 'use strict';
 
-jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-  canUseDOM: true,
+jest.mock('../ExecutionEnvironment', () => ({
+  isServer: false,
 }));
 
 const React = require('react');
diff --git a/packages/relay-experimental/__tests__/useRefetchableFragmentNode-test.js b/packages/relay-experimental/__tests__/useRefetchableFragmentNode-test.js
index e308913c4872e..0d2b2133d0a02 100644
--- a/packages/relay-experimental/__tests__/useRefetchableFragmentNode-test.js
+++ b/packages/relay-experimental/__tests__/useRefetchableFragmentNode-test.js
@@ -119,8 +119,8 @@ describe('useRefetchableFragmentNode', () => {
     jest.mock('scheduler', () => {
       return jest.requireActual('scheduler/unstable_mock');
     });
-    jest.mock('fbjs/lib/ExecutionEnvironment', () => ({
-      canUseDOM: () => true,
+    jest.mock('../ExecutionEnvironment', () => ({
+      isServer: false,
     }));
     renderSpy = jest.fn();
 
diff --git a/packages/relay-experimental/preloadQuery_DEPRECATED.js b/packages/relay-experimental/preloadQuery_DEPRECATED.js
index a8480e3dc67da..33c8e676b12a3 100644
--- a/packages/relay-experimental/preloadQuery_DEPRECATED.js
+++ b/packages/relay-experimental/preloadQuery_DEPRECATED.js
@@ -13,7 +13,7 @@
 
 'use strict';
 
-const ExecutionEnvironment = require('fbjs/lib/ExecutionEnvironment');
+const ExecutionEnvironment = require('./ExecutionEnvironment');
 
 const invariant = require('invariant');
 
@@ -159,7 +159,7 @@ function preloadQueryDeduped<TQuery: OperationType>(
             kind: 'cache',
             name: params.name,
           };
-    if (ExecutionEnvironment.canUseDOM && prevQueryEntry == null) {
+    if (!ExecutionEnvironment.isServer && prevQueryEntry == null) {
       setTimeout(() => {
         // Clear the cache entry after the default timeout
         // null-check for Flow
@@ -191,7 +191,7 @@ function preloadQueryDeduped<TQuery: OperationType>(
       subject,
       subscription: source
         .finally(() => {
-          if (!ExecutionEnvironment.canUseDOM) {
+          if (ExecutionEnvironment.isServer) {
             return;
           }
           setTimeout(() => {