Index: mdtraj/setup.py
===================================================================
--- mdtraj.orig/setup.py	2023-01-18 15:26:51.424826255 +0100
+++ mdtraj/setup.py	2023-01-18 15:26:51.420826223 +0100
@@ -298,6 +298,10 @@
 
         for e in extensions:
             e.include_dirs.append(np.get_include())
-        metadata['ext_modules'] = cythonize(extensions, language_level=sys.version_info[0])
+        metadata['ext_modules'] = cythonize(
+            extensions,
+            language_level=sys.version_info[0],
+            force=True,
+        )
 
     setup(**metadata)