diff --git a/COPYING.picolibc b/COPYING.picolibc
index 933f83d29a..238ff42489 100644
--- a/COPYING.picolibc
+++ b/COPYING.picolibc
@@ -1263,6 +1263,7 @@ Files: newlib/libc/include/stdnoreturn.h
  newlib/libc/tinystdio/funlockfile.c
  newlib/libc/tinystdio/funopen.c
  newlib/libm/fenv/fenv.c
+ scripts/validate-cdefs
  test/test-cplusplus.cpp
  test/test-ctype.c
  test/test-funopen.c
diff --git a/scripts/validate-cdefs b/scripts/validate-cdefs
index 1cba4e65d5..ad4dd2b577 100755
--- a/scripts/validate-cdefs
+++ b/scripts/validate-cdefs
@@ -1,4 +1,38 @@
 #!/bin/bash
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+# Copyright © 2024 Keith Packard
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above
+#    copyright notice, this list of conditions and the following
+#    disclaimer in the documentation and/or other materials provided
+#    with the distribution.
+#
+# 3. Neither the name of the copyright holder nor the names of its
+#    contributors may be used to endorse or promote products derived
+#    from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+# INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+# OF THE POSSIBILITY OF SUCH DAMAGE.
+#
 
 input="$1"
 shift