diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 8c4003b73..9b26d9e6c 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -597,7 +597,7 @@ class Backend:
                              feed: T.Optional[str] = None,
                              force_serialize: bool = False,
                              env: T.Optional[mesonlib.EnvironmentVariables] = None,
-                             verbose: bool = False) -> T.Tuple[T.Sequence[T.Union[str, File, build.Target, programs.ExternalProgram]], str]:
+                             verbose: bool = False) -> T.Tuple[T.List[str], str]:
         '''
         Serialize an executable for running with a generator or a custom target
         '''