diff --git a/src/main.cpp b/src/main.cpp
index e0db0ad..f68de3e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Apache-2.0
+
 #include "btop.hpp"
 
 #include <iterator>