diff --git a/muk_utils/tools/utils_os.py b/muk_utils/tools/utils_os.py
index 5201d9e..e68249d 100644
--- a/muk_utils/tools/utils_os.py
+++ b/muk_utils/tools/utils_os.py
@@ -48,7 +48,7 @@ def unique_name(name, names, escape_suffix=False):
             name = compute_name(name, suffix, escape_suffix)
         return name
     
-def get_extension(filename, mimetype):
+def get_extension(binary, filename, mimetype):
     if not mimetype and not filename:
         mimetype = guess_mimetype(binary, default=False)
     if not mimetype and filename: