diff --git a/src/Microsoft.VisualStudio.Threading/AsyncQueue`1.cs b/src/Microsoft.VisualStudio.Threading/AsyncQueue`1.cs
index 324aa326..10c7624b 100644
--- a/src/Microsoft.VisualStudio.Threading/AsyncQueue`1.cs
+++ b/src/Microsoft.VisualStudio.Threading/AsyncQueue`1.cs
@@ -161,6 +161,7 @@ public void Complete()
/// Adds an element to the tail of the queue.
///
/// The value to add.
+ /// Thrown if has already been called. Use to avoid an exception in this case.
public void Enqueue(T value)
{
if (!this.TryEnqueue(value))