diff --git a/ICSharpCode.Decompiler/Instrumentation/DecompilerEventSource.cs b/ICSharpCode.Decompiler/Instrumentation/DecompilerEventSource.cs
index def7ec5bb..aaacec5f9 100644
--- a/ICSharpCode.Decompiler/Instrumentation/DecompilerEventSource.cs
+++ b/ICSharpCode.Decompiler/Instrumentation/DecompilerEventSource.cs
@@ -1,4 +1,22 @@
-using System.Diagnostics.Tracing;
+// Copyright (c) 2021 Christoph Wille
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System.Diagnostics.Tracing;
 
 namespace ICSharpCode.Decompiler.Instrumentation
 {