diff --git a/src/main/java/io/reactivex/subjects/UnicastSubject.java b/src/main/java/io/reactivex/subjects/UnicastSubject.java
index 1b14fd364d..5a194c4ee5 100644
--- a/src/main/java/io/reactivex/subjects/UnicastSubject.java
+++ b/src/main/java/io/reactivex/subjects/UnicastSubject.java
@@ -167,8 +167,9 @@ public State(int capacityHint, Runnable onCancelled) {
         @Override
         public void subscribe(Subscriber<? super T> s) {
             if (once == 0 && ONCE.compareAndSet(this, 0, 1)) {
-                SUBSCRIBER.lazySet(this, s);
                 s.onSubscribe(this);
+                SUBSCRIBER.lazySet(this, s); // full barrier in drain
+                drain();
             } else {
                 if (done) {
                     Throwable e = error;
diff --git a/src/main/java/io/reactivex/subjects/nbp/NbpUnicastSubject.java b/src/main/java/io/reactivex/subjects/nbp/NbpUnicastSubject.java
index ae29966819..e0f77b107e 100644
--- a/src/main/java/io/reactivex/subjects/nbp/NbpUnicastSubject.java
+++ b/src/main/java/io/reactivex/subjects/nbp/NbpUnicastSubject.java
@@ -144,8 +144,8 @@ public State(int capacityHint, Runnable onCancelled) {
         @Override
         public void accept(NbpSubscriber<? super T> s) {
             if (once == 0 && ONCE.compareAndSet(this, 0, 1)) {
-                SUBSCRIBER.lazySet(this, s);
                 s.onSubscribe(this);
+                SUBSCRIBER.lazySet(this, s); // full barrier in drain
                 drain();
             } else {
                 s.onSubscribe(EmptyDisposable.INSTANCE);