diff --git a/contrib/devtools/copyright_header.py b/contrib/devtools/copyright_header.py
index f2987f22605..29d1ed87ff3 100755
--- a/contrib/devtools/copyright_header.py
+++ b/contrib/devtools/copyright_header.py
@@ -34,7 +34,7 @@ EXCLUDE_DIRS = [
     "src/univalue/",
 ]
 
-INCLUDE = ['*.h', '*.cpp', '*.cc', '*.c', '*.py']
+INCLUDE = ['*.h', '*.cpp', '*.cc', '*.c', '*.mm', '*.py']
 INCLUDE_COMPILED = re.compile('|'.join([fnmatch.translate(m) for m in INCLUDE]))
 
 def applies_to_file(filename):