diff --git a/src/cache/inmemory/inMemoryCache.ts b/src/cache/inmemory/inMemoryCache.ts
index aa988941e1d..64a90cdac03 100644
--- a/src/cache/inmemory/inMemoryCache.ts
+++ b/src/cache/inmemory/inMemoryCache.ts
@@ -181,6 +181,11 @@ export class InMemoryCache extends ApolloCache<NormalizedCacheObject> {
     }
     return () => {
       this.watches.delete(watch);
+      this.watchDep.dirty(watch);
+      // Remove this watch from the LRU cache managed by the
+      // maybeBroadcastWatch OptimisticWrapperFunction, to prevent memory
+      // leaks involving the closure of watch.callback.
+      this.maybeBroadcastWatch.forget(watch);
     };
   }