diff --git a/lib/redmine_dmsf/patches/easy_crm_case_patch.rb b/lib/redmine_dmsf/patches/easy_crm_case_patch.rb
index e046b3cc..7748044c 100644
--- a/lib/redmine_dmsf/patches/easy_crm_case_patch.rb
+++ b/lib/redmine_dmsf/patches/easy_crm_case_patch.rb
@@ -123,11 +123,11 @@ module RedmineDmsf
       end
 
       def dmsf_files
-        system_folder&.dmsf_files
+        system_folder&.dmsf_files || []
       end
 
       def dmsf_links
-        system_folder&.dmsf_links
+        system_folder&.dmsf_links || []
       end
 
       def delete_system_folder