diff --git a/lean/components/config/lean_config_manager.py b/lean/components/config/lean_config_manager.py
index 0a765922..aa26ab16 100644
--- a/lean/components/config/lean_config_manager.py
+++ b/lean/components/config/lean_config_manager.py
@@ -11,7 +11,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from os.path import normcase
+from os.path import normcase, normpath
 from pathlib import Path
 from typing import Any, Dict, Optional, List
 
@@ -98,7 +98,7 @@ def get_known_lean_config_paths(self) -> List[Path]:
         :return: a list of paths to Lean config files that were used in the past
         """
         lean_config_paths = self._cache_storage.get("known-lean-config-paths", [])
-        lean_config_paths = [Path(normcase(p)) for p in lean_config_paths if Path(p).is_file()]
+        lean_config_paths = [Path(normpath(normcase(p))) for p in lean_config_paths if Path(p).is_file()]
         lean_config_paths = list(set(lean_config_paths))
 
         self._cache_storage.set("known-lean-config-paths", [str(p) for p in lean_config_paths])
diff --git a/tests/components/config/test_lean_config_manager.py b/tests/components/config/test_lean_config_manager.py
index 7ea51e20..ee7dcd99 100644
--- a/tests/components/config/test_lean_config_manager.py
+++ b/tests/components/config/test_lean_config_manager.py
@@ -100,6 +100,16 @@ def test_get_known_lean_config_path_with_duplicated_paths() -> None:
 
     assert manager.get_known_lean_config_paths() == [Path.cwd() / "custom-lean.json"]
 
+def test_get_known_lean_config_path_normalizes_path_and_case() -> None:
+    custom_config_path = Path.cwd() / "//folder//..//custom-lean.json//"
+    custom_config_path.touch()
+    custom_config_path.write_text("{}", encoding="utf-8")
+
+    manager = _create_lean_config_manager()
+    manager.set_default_lean_config_path(custom_config_path)
+
+    assert manager.get_known_lean_config_paths() == [Path(os.path.normcase(Path.cwd() / "/custom-lean.json"))]
+
 def test_get_cli_root_directory_returns_path_to_directory_containing_config_file() -> None:
     create_fake_lean_cli_directory()