diff --git a/lib/oga/css/parser.y b/lib/oga/css/parser.y
index 17d8cc0..f5b9776 100644
--- a/lib/oga/css/parser.y
+++ b/lib/oga/css/parser.y
@@ -505,6 +505,8 @@ end
     else
       mod_val = s(:int, 1)
     end
+
+    return mod_val
   end
 
 # vim: set ft=racc: