diff --git a/src/clos/standard.lsp b/src/clos/standard.lsp
index 3d77b553d..09023f355 100644
--- a/src/clos/standard.lsp
+++ b/src/clos/standard.lsp
@@ -414,8 +414,9 @@ because it contains a reference to the undefined class~%  ~A"
 	 (error "~a is not a valid class specifier." class-or-symbol))
 	((find-class class-or-symbol fail))
 	(t
-	 (warn 'style-warning
-	       "Class ~A has been forward referenced." class-or-symbol)
+	 (warn 'ext::simple-style-warning
+	       :format-control "Class ~A has been forward referenced."
+	       :format-arguments (list class-or-symbol))
 	 (ensure-class class-or-symbol
 		       :metaclass 'forward-referenced-class
 		       :direct-superclasses (list (find-class 'standard-object))