diff --git a/mesonbuild/minstall.py b/mesonbuild/minstall.py
index 0bb1691ebc61..2db4472d160c 100644
--- a/mesonbuild/minstall.py
+++ b/mesonbuild/minstall.py
@@ -139,7 +139,6 @@ def append_to_log(lf: T.TextIO, line: str) -> None:
         lf.write('\n')
     lf.flush()
 
-
 def set_chown(path: str, user: T.Union[str, int, None] = None,
               group: T.Union[str, int, None] = None,
               dir_fd: T.Optional[int] = None, follow_symlinks: bool = True) -> None:
@@ -150,10 +149,23 @@ def set_chown(path: str, user: T.Union[str, int, None] = None,
     # Not nice, but better than actually rewriting shutil.chown until
     # this python bug is fixed: https://bugs.python.org/issue18108
 
+    # This is running into a problem where this may not match any of signatures
+    # of `shtil.chown`, which (simplified) are:
+    #  chown(path: int | AnyPath, user: int | str, group: None = None)
+    #  chown(path: int | AnyPath, user: None, group: int | str)
+    # We cannot through easy coercion of the type system force it to say:
+    #  - user is non null and group is null
+    #  - user is null and group is non null
+    #  - user is non null and group is non null
+    #
+    # This is checked by the only (current) caller, but let's be sure that the
+    # call we're making to `shutil.chown` is actually valid.
+    assert user is not None or group is not None, 'ensure that calls to chown are valid'
+
     if sys.version_info >= (3, 13):
         # pylint: disable=unexpected-keyword-arg
         # cannot handle sys.version_info, https://github.com/pylint-dev/pylint/issues/9622
-        shutil.chown(path, user, group, dir_fd=dir_fd, follow_symlinks=follow_symlinks)
+        shutil.chown(path, user, group, dir_fd=dir_fd, follow_symlinks=follow_symlinks)  # type: ignore[call-overload]
     else:
         real_os_chown = os.chown