diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index ac0168003285..6c7e7092d31e 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -871,6 +871,7 @@ def object_filename_from_source(self, target: build.BuildTarget, source: 'FileOr
             return os.path.join(targetdir, ret)
         return ret
 
+    @lru_cache(maxsize=None)
     def _determine_ext_objs(self, extobj: 'build.ExtractedObjects') -> T.List[str]:
         result: T.List[str] = []