diff --git a/lib/ModuleGraph.js b/lib/ModuleGraph.js
index e67e7dbddbd..4e96315a56e 100644
--- a/lib/ModuleGraph.js
+++ b/lib/ModuleGraph.js
@@ -128,6 +128,9 @@ class ModuleGraph {
 
 		/** @type {Map<Module, WeakTupleMap<any, any>>} */
 		this._moduleMemCaches = undefined;
+
+		/** @type {string} */
+		this._cacheStage = undefined;
 	}
 
 	/**