diff --git a/src/main/java/io/reactivex/Flowable.java b/src/main/java/io/reactivex/Flowable.java
index 18ed618512..1115eba74e 100644
--- a/src/main/java/io/reactivex/Flowable.java
+++ b/src/main/java/io/reactivex/Flowable.java
@@ -16983,7 +16983,7 @@ public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
      * @since 2.0
      */
     @CheckReturnValue
-    @BackpressureSupport(BackpressureKind.NONE)
+    @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Observable<T> toObservable() {
         return RxJavaPlugins.onAssembly(new ObservableFromPublisher<T>(this));