diff --git a/mesonbuild/utils/universal.py b/mesonbuild/utils/universal.py
index 904cbbcfe7d7..039b0d91e5f1 100644
--- a/mesonbuild/utils/universal.py
+++ b/mesonbuild/utils/universal.py
@@ -1346,7 +1346,7 @@ def do_conf_str(src: str, data: T.List[str], confdata: 'ConfigurationData',
         raise MesonException('Invalid variable format')
 
 def do_conf_str_meson(src: str, data: T.List[str], confdata: 'ConfigurationData', subproject: T.Optional[SubProject] = None) -> T.Tuple[T.List[str], T.Set[str], bool]:
-    variable_format = "meson"
+    variable_format: Literal["meson"] = "meson"
 
     regex = get_variable_regex(variable_format)
 
@@ -1372,10 +1372,10 @@ def do_conf_str_meson(src: str, data: T.List[str], confdata: 'ConfigurationData'
     return result, missing_variables, confdata_useless
 
 def do_conf_str_cmake(src: str, data: T.List[str], confdata: 'ConfigurationData', at_only: bool, subproject: T.Optional[SubProject] = None) -> T.Tuple[T.List[str], T.Set[str], bool]:
+
+    variable_format: Literal["cmake", "cmake@"] = "cmake"
     if at_only:
         variable_format = "cmake@"
-    else:
-        variable_format = "cmake"
 
     regex = get_variable_regex(variable_format)