diff --git a/layouts/_default/single.html b/layouts/_default/single.html
index 984cd33..51c6e2f 100644
--- a/layouts/_default/single.html
+++ b/layouts/_default/single.html
@@ -16,7 +16,7 @@
       "image" (.Resources.GetMatch "featured")
       "alt" .Params.featured.alt
       "sizes" (slice 320 480 600 800)
-      "classes" "shadow featured") }}
+      "classes" (slice "shadow" "featured")) }}
 
   {{ .Content }}
   {{ partial "terms.html" (dict "taxonomy" "tags" "page" .) }}