diff --git a/tools/distrib/check_copyright.py b/tools/distrib/check_copyright.py
index 6c66a291808..2d461435859 100755
--- a/tools/distrib/check_copyright.py
+++ b/tools/distrib/check_copyright.py
@@ -72,6 +72,9 @@ LICENSE_PREFIX = {
   '.php':       r'\s*\*\s*',
   '.js':        r'\s*\*\s*',
   '.py':        r'#\s*',
+  '.pyx':       r'# %s',
+  '.pxd':       r'# %s',
+  '.pxi':       r'# %s',
   '.rb':        r'#\s*',
   '.sh':        r'#\s*',
   '.proto':     r'//\s*',