diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index 7d3502cb1cac0..cc4285ab1137e 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -61,7 +61,7 @@ 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 b093ebf81b202..ece34f2977090 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
@@ -63,7 +63,7 @@ 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;