diff --git a/src/Avalonia.Base/Reactive/SingleSubscriberObservableBase.cs b/src/Avalonia.Base/Reactive/SingleSubscriberObservableBase.cs
index 5e3a6bf79a..53a0b43c63 100644
--- a/src/Avalonia.Base/Reactive/SingleSubscriberObservableBase.cs
+++ b/src/Avalonia.Base/Reactive/SingleSubscriberObservableBase.cs
@@ -51,10 +51,11 @@ namespace Avalonia.Reactive
 
         protected void PublishCompleted()
         {
+            _completed = true;
+
             if (_observer != null)
             {
                 _observer.OnCompleted();
-                _completed = true;
                 Unsubscribed();
                 _observer = null;
             }
@@ -62,10 +63,11 @@ namespace Avalonia.Reactive
 
         protected void PublishError(Exception error)
         {
+            _error = error;
+
             if (_observer != null)
             {
                 _observer.OnError(error);
-                _error = error;
                 Unsubscribed();
                 _observer = null;
             }