diff --git a/TunnelVisionLabs.ReferenceAssemblyAnnotator/AnnotatorBuildTask.cs b/TunnelVisionLabs.ReferenceAssemblyAnnotator/AnnotatorBuildTask.cs
index 20f6c71..04bbdb6 100644
--- a/TunnelVisionLabs.ReferenceAssemblyAnnotator/AnnotatorBuildTask.cs
+++ b/TunnelVisionLabs.ReferenceAssemblyAnnotator/AnnotatorBuildTask.cs
@@ -102,9 +102,16 @@ public override bool Execute()
 
             string sourceDocumentation = Path.ChangeExtension(unannotatedReferenceAssembly, ".xml");
             string targetDocumentation = Path.ChangeExtension(outputAssembly, ".xml");
-            if (File.Exists(sourceDocumentation))
+            if (File.Exists(sourceDocumentation) && !File.Exists(targetDocumentation))
             {
-                File.Copy(sourceDocumentation, targetDocumentation);
+                try
+                {
+                    File.Copy(sourceDocumentation, targetDocumentation);
+                }
+                catch (IOException ex) when ((WindowsErrorCode)ex.HResult == WindowsErrorCode.FileExists)
+                {
+                }
+
                 GeneratedDocumentationFiles = new[] { new TaskItem(targetDocumentation) };
             }
             else
diff --git a/TunnelVisionLabs.ReferenceAssemblyAnnotator/WindowsErrorCode.cs b/TunnelVisionLabs.ReferenceAssemblyAnnotator/WindowsErrorCode.cs
new file mode 100644
index 0000000..64e8d7d
--- /dev/null
+++ b/TunnelVisionLabs.ReferenceAssemblyAnnotator/WindowsErrorCode.cs
@@ -0,0 +1,13 @@
+// Copyright (c) Tunnel Vision Laboratories, LLC. All Rights Reserved.
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+namespace TunnelVisionLabs.ReferenceAssemblyAnnotator
+{
+    internal enum WindowsErrorCode : ushort
+    {
+        /// <summary>
+        /// https://docs.microsoft.com/en-us/windows/win32/debug/system-error-codes--0-499-#error_file_exists
+        /// </summary>
+        FileExists = 80,
+    }
+}