diff --git a/options.xhtml b/options.xhtml
index 4df6d864..29a23c95 100644
--- a/options.xhtml
+++ b/options.xhtml
@@ -6894,7 +6894,7 @@ null or (submodule)</p>
 <dd>
 <p>Package providing the theme. This package will be installed
 to your profile. If <code class="literal">null</code> then the theme
-is assumed to already be available in your profile.</p>
+is assumed to already be available in your profile.</p><p>For the theme to apply to GTK 4, this option is mandatory.</p>
 
 <p><span class="emphasis"><em>Type:</em></span>
 null or package</p>