diff --git a/packages/react-reconciler/src/ReactFiber.js b/packages/react-reconciler/src/ReactFiber.js
index e0724b4a9da71..703091ddd4aae 100644
--- a/packages/react-reconciler/src/ReactFiber.js
+++ b/packages/react-reconciler/src/ReactFiber.js
@@ -296,11 +296,15 @@ function createFiberImplObject(
   }
 
   if (__DEV__) {
+    // This isn't directly used but is handy for debugging internals:
     fiber._debugInfo = null;
     fiber._debugOwner = null;
+    if (enableOwnerStacks) {
+      fiber._debugStack = null;
+      fiber._debugTask = null;
+    }
     fiber._debugNeedsRemount = false;
     fiber._debugHookTypes = null;
-
     if (!hasBadMapPolyfill && typeof Object.preventExtensions === 'function') {
       Object.preventExtensions(fiber);
     }