diff --git a/themes/luci-theme-bootstrap/htdocs/luci-static/bootstrap/cascade.css b/themes/luci-theme-bootstrap/htdocs/luci-static/bootstrap/cascade.css
index 1001281b5c..22c49fdde1 100644
--- a/themes/luci-theme-bootstrap/htdocs/luci-static/bootstrap/cascade.css
+++ b/themes/luci-theme-bootstrap/htdocs/luci-static/bootstrap/cascade.css
@@ -1266,6 +1266,8 @@ footer {
 }
 
 .cbi-input-invalid,
+.cbi-input-invalid.cbi-dropdown,
+.cbi-input-invalid.cbi-dropdown:not([open]) > ul > li,
 .cbi-value-error input {
 	color: #f00;
 	border-color: #f00;