diff --git a/server/mergin/sync/models.py b/server/mergin/sync/models.py
index 30c244a0..705a5e18 100644
--- a/server/mergin/sync/models.py
+++ b/server/mergin/sync/models.py
@@ -744,7 +744,7 @@ def __init__(
             fh.path: fh.id
             for fh in FileHistory.query.filter(
                 FileHistory.id.in_(
-                    self.project.latest_project_files.file_history_ids or {}
+                    self.project.latest_project_files.file_history_ids
                 )
             ).all()
         }
diff --git a/server/mergin/tests/test_project_controller.py b/server/mergin/tests/test_project_controller.py
index 216f4b48..74421147 100644
--- a/server/mergin/tests/test_project_controller.py
+++ b/server/mergin/tests/test_project_controller.py
@@ -37,7 +37,7 @@
     ProjectFilePath,
 )
 from ..sync.files import ChangesSchema
-from ..sync.schemas import ProjectListSchema, ProjectSchema
+from ..sync.schemas import ProjectListSchema
 from ..sync.utils import generate_checksum, is_versioned_file
 from ..auth.models import User, UserProfile
 
@@ -58,6 +58,7 @@
     login,
     file_info,
     login_as_admin,
+    upload_file_to_project,
 )
 from ..config import Configuration
 from ..sync.config import Configuration as SyncConfiguration
@@ -2461,3 +2462,21 @@ def test_delete_diff_file(client):
         change=PushChangeType.DELETE.value,
     ).first()
     assert fh.path == "base.gpkg" and fh.diff is None
+
+
+def test_cache_files_ids(client):
+    """Test caching latest project files when it is None"""
+    user = User.query.filter_by(username="mergin").first()
+    test_workspace = create_workspace()
+    project = create_project("no_file_history", test_workspace, user)
+    db.session.commit()
+    assert project.latest_project_files.file_history_ids is not None
+    project.latest_project_files.file_history_ids = None
+    db.session.commit()
+    assert project.latest_project_files.file_history_ids is None
+    # uploading to project caches
+    filename = "test.txt"
+    upload_file_to_project(project, filename, client)
+    fp = ProjectFilePath.query.filter_by(project_id=project.id, path=filename).first()
+    fh = FileHistory.query.filter_by(file_path_id=fp.id).first()
+    assert project.latest_project_files.file_history_ids == [fh.id]