diff --git a/src/cmp/cmpenv.lsp b/src/cmp/cmpenv.lsp
index fd4939a02044d0cff328acf5f2a0a9181d064b27..89b7f3034c1483a41055a620c8c05198f42be301 100644
--- a/src/cmp/cmpenv.lsp
+++ b/src/cmp/cmpenv.lsp
@@ -104,7 +104,7 @@
                ((or (endp (cdar return-types))
                     (member (cadar return-types) '(&optional &rest &key)))
                 t)
-               (t (type-filter (cadar return-types)))))
+               (t (type-filter (car return-types) t))))
         (t (type-filter (car return-types)))))
 
 (defun add-function-proclamation (fname decl)