diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index b332c485a0862..8281009889b21 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -53,7 +53,7 @@ export const enableLegacyHidden = false;
 
 export const enableTransitionTracing = false;
 
-export const useModernStrictMode = false;
+export const useModernStrictMode = true;
 export const enableDO_NOT_USE_disableStrictPassiveEffect = false;
 export const enableFizzExternalRuntime = true;
 export const enableDeferRootSchedulingToMicrotask = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
index 20ecdb44b4717..d1fe7629901ec 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
@@ -55,7 +55,7 @@ export const enableLegacyHidden = false;
 
 export const enableTransitionTracing = false;
 
-export const useModernStrictMode = false;
+export const useModernStrictMode = true;
 export const enableDO_NOT_USE_disableStrictPassiveEffect = false;
 export const enableFizzExternalRuntime = false;
 export const enableDeferRootSchedulingToMicrotask = true;