diff --git a/bricktracker/sql/migrations/init.sql b/bricktracker/sql/migrations/init.sql
index f243b8c..85defbb 100644
--- a/bricktracker/sql/migrations/init.sql
+++ b/bricktracker/sql/migrations/init.sql
@@ -58,4 +58,9 @@ CREATE TABLE IF NOT EXISTS missing (
         u_id TEXT
     );
 
+-- Fix a bug where 'None' was inserted in missing instead of NULL
+UPDATE missing
+SET element_id = NULL
+WHERE element_id = 'None';
+
 COMMIT;
\ No newline at end of file
diff --git a/bricktracker/sql/missing/count_none.sql b/bricktracker/sql/missing/count_none.sql
new file mode 100644
index 0000000..3f4073b
--- /dev/null
+++ b/bricktracker/sql/missing/count_none.sql
@@ -0,0 +1,3 @@
+SELECT count(*) AS count
+FROM missing
+WHERE element_id = 'None'
diff --git a/bricktracker/views/admin.py b/bricktracker/views/admin.py
index 6315d60..2a5addf 100644
--- a/bricktracker/views/admin.py
+++ b/bricktracker/views/admin.py
@@ -36,6 +36,7 @@ def admin() -> str:
     counters: dict[str, int] = {}
     exception: Exception | None = None
     is_init: bool = False
+    count_none: int = 0
 
     # This view needs to be protected against SQL errors
     try:
@@ -43,6 +44,11 @@ def admin() -> str:
 
         if is_init:
             counters = BrickSQL.count_records()
+
+        record = BrickSQL().fetchone('missing/count_none')
+        if record is not None:
+            count_none = record['count']
+
     except Exception as e:
         exception = e
 
@@ -67,6 +73,7 @@ def admin() -> str:
         'admin.html',
         configuration=BrickConfigurationList.list(),
         counters=counters,
+        count_none=count_none,
         error=request.args.get('error'),
         exception=exception,
         instructions=BrickInstructionsList(),
diff --git a/templates/admin/database.html b/templates/admin/database.html
index 1710d7d..7b15397 100644
--- a/templates/admin/database.html
+++ b/templates/admin/database.html
@@ -13,6 +13,18 @@
     </form>
   </div>
 {% else %}
+  {% if count_none %}
+    <div class="alert alert-warning" role="alert">
+      <p>
+        Your <code>missing</code> table contains <code>"None"</code> entries (instead of <code>NULL</code>). <br>
+        This can lead to "phantom" missing parts appearing in your sets if you are coming from the original version of BrickTracker.
+      </p>
+      <hr>
+      <form action="{{ url_for('admin.init_database') }}" method="post" class="text-end">
+          <button type="submit" class="btn btn-warning"><i class="ri-capsule-line"></i> Apply the fix</button>
+      </form>
+    </div>
+  {% endif %}
   <p><i class="ri-checkbox-circle-line"></i> The database is initialized.</p>
   <p>
     <a href="{{ url_for('admin.download_database') }}" class="btn btn-primary" role="button"><i class="ri-download-line"></i> Download the database file</a>