diff --git a/Sources/P4Compiler/Visitor.swift b/Sources/P4Compiler/Visitor.swift
index 7480322..4f212da 100644
--- a/Sources/P4Compiler/Visitor.swift
+++ b/Sources/P4Compiler/Visitor.swift
@@ -1,3 +1,20 @@
+// p4rse, Copyright 2026, Will Hawkins
+//
+// This file is part of p4rse.
+//
+// This file is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
 import Common
 
 public struct ASTVisitorDriver {