diff --git a/types/tinymce/index.d.ts b/types/tinymce/index.d.ts
index 2791871593..897199a214 100644
--- a/types/tinymce/index.d.ts
+++ b/types/tinymce/index.d.ts
@@ -133,7 +133,7 @@ export interface Settings {
 
   body_id?: string;
 
-  content_css?: string;
+  content_css?: string | string[];
 
   content_style?: string;