diff --git a/src/components/fetchhelper.ts b/src/components/fetchhelper.ts
index 7122ced1..b4f10a3e 100644
--- a/src/components/fetchhelper.ts
+++ b/src/components/fetchhelper.ts
@@ -126,7 +126,7 @@ export async function ajax(request: any): Promise<Response | string> {
             return response.json();
         } else if (
             request.dataType === 'text' ||
-            (response.headers.get('Content-Type') || '')
+            (response.headers.get('Content-Type') ?? '')
                 .toLowerCase()
                 .startsWith('text/')
         ) {