diff --git a/test/fixtures/dmsf_links.yml b/test/fixtures/dmsf_links.yml
index ab1128ce..69fbce27 100644
--- a/test/fixtures/dmsf_links.yml
+++ b/test/fixtures/dmsf_links.yml
@@ -6,9 +6,9 @@ folder_link:
   target_type: DmsfFolder
   name: folder1_link
   project_id: 1
-  dmsf_folder_id: nil
+  dmsf_folder_id: NULL
   deleted: 0
-  deleted_by_user_id: nil
+  deleted_by_user_id: NULL
   created_at: <%= DateTime.current %>
   updated_at: <%= DateTime.current %>
   
@@ -21,7 +21,7 @@ file_link:
   project_id: 1
   dmsf_folder_id: 1
   deleted: 0
-  deleted_by_user_id: nil
+  deleted_by_user_id: NULL
   created_at: <%= DateTime.current %>
   updated_at: <%= DateTime.current %>
 
@@ -32,9 +32,9 @@ folder_link2:
   target_type: DmsfFolder
   name: folder4_link
   project_id: 2
-  dmsf_folder_id: nil
+  dmsf_folder_id: NULL
   deleted: 0
-  deleted_by_user_id: nil
+  deleted_by_user_id: NULL
   created_at: <%= DateTime.current %>
   updated_at: <%= DateTime.current %>
   
@@ -45,9 +45,9 @@ file_link2:
   target_type: DmsfFile
   name: test_link
   project_id: 1
-  dmsf_folder_id: nil
+  dmsf_folder_id: NULL
   deleted: 0
-  deleted_by_user_id: nil
+  deleted_by_user_id: NULL
   created_at: <%= DateTime.current %>
   updated_at: <%= DateTime.current %>
 
@@ -60,6 +60,6 @@ url_link:
   project_id: 1
   external_url: 'https://www.kontron.com'
   deleted: 0
-  deleted_by_user_id: nil
+  deleted_by_user_id: NULL
   created_at: <%= DateTime.current %>
   updated_at: <%= DateTime.current %>
\ No newline at end of file