diff --git a/ext/puma_http11/http11_parser.c b/ext/puma_http11/http11_parser.c
index d379582c..725eb908 100644
--- a/ext/puma_http11/http11_parser.c
+++ b/ext/puma_http11/http11_parser.c
@@ -3,6 +3,7 @@
 /**
  * Copyright (c) 2005 Zed A. Shaw
  * You can redistribute it and/or modify it under the same terms as Ruby.
+ * License 3-clause BSD
  */
 #include "http11_parser.h"
 #include <stdio.h>
diff --git a/ext/puma_http11/http11_parser.h b/ext/puma_http11/http11_parser.h
index c4ce4786..eb0afd44 100644
--- a/ext/puma_http11/http11_parser.h
+++ b/ext/puma_http11/http11_parser.h
@@ -1,6 +1,7 @@
 /**
  * Copyright (c) 2005 Zed A. Shaw
  * You can redistribute it and/or modify it under the same terms as Ruby.
+ * License 3-clause BSD
  */
 
 #ifndef http11_parser_h
diff --git a/ext/puma_http11/http11_parser.rl b/ext/puma_http11/http11_parser.rl
index 02da6d3c..ac01d58a 100644
--- a/ext/puma_http11/http11_parser.rl
+++ b/ext/puma_http11/http11_parser.rl
@@ -1,6 +1,7 @@
 /**
  * Copyright (c) 2005 Zed A. Shaw
  * You can redistribute it and/or modify it under the same terms as Ruby.
+ * License 3-clause BSD
  */
 #include "http11_parser.h"
 #include <stdio.h>
diff --git a/ext/puma_http11/puma_http11.c b/ext/puma_http11/puma_http11.c
index 8fa3083f..79e706d0 100644
--- a/ext/puma_http11/puma_http11.c
+++ b/ext/puma_http11/puma_http11.c
@@ -1,6 +1,7 @@
 /**
  * Copyright (c) 2005 Zed A. Shaw
  * You can redistribute it and/or modify it under the same terms as Ruby.
+ * License 3-clause BSD
  */
 
 #define RSTRING_NOT_MODIFIED 1