diff --git a/sphinx/themes/basic/layout.html b/sphinx/themes/basic/layout.html
index c7312ffd0..2e20fbb66 100644
--- a/sphinx/themes/basic/layout.html
+++ b/sphinx/themes/basic/layout.html
@@ -109,7 +109,7 @@
       {%- if css|attr("rel") %}
     <link rel="{{ css.rel }}" href="{{ pathto(css.filename, 1) }}" type="text/css"{% if css.title is not none %} title="{{ css.title }}"{% endif %} />
       {%- else %}
-    <link href="{{ pathto(css, 1) }}" type="text/css" />
+    <link rel="stylesheet" href="{{ pathto(css, 1) }}" type="text/css" />
       {%- endif %}
     {%- endfor %}
 {%- endmacro %}