diff --git a/frontend/src/pages/ContactsList.tsx b/frontend/src/pages/ContactsList.tsx
index 423f159..a9719e1 100644
--- a/frontend/src/pages/ContactsList.tsx
+++ b/frontend/src/pages/ContactsList.tsx
@@ -79,7 +79,7 @@ export function ContactsListPage() {
 
   // Build custom field defs for filter/sort/group functions
   const customDefsForFunctions = useMemo(() => {
-    if (!customFieldDefs || customFieldDefs.items.length === 0) return undefined;
+    if (!customFieldDefs || !customFieldDefs.items || customFieldDefs.items.length === 0) return undefined;
     return customFieldDefs.items
       .filter((def) => def.is_active)
       .map((def) => ({