diff --git a/core.scm b/core.scm
index 2bbed0b..3ecdd81 100644
--- a/core.scm
+++ b/core.scm
@@ -517,7 +517,7 @@
 
   (define (lookup id)
     (cond ((find-id id (##sys#current-environment)))
-	  ((##sys#get id '##core#macro-alias))
+	  ((##sys#get id '##core#macro-alias) symbol? => values)
 	  (else id)))
 
   (define (macro-alias var)
diff --git a/eval.scm b/eval.scm
index f1c5bb6..aeaf173 100644
--- a/eval.scm
+++ b/eval.scm
@@ -92,7 +92,7 @@
 
       (define (rename var)
 	(cond ((find-id var (##sys#current-environment)))
-	      ((##sys#get var '##core#macro-alias))
+	      ((##sys#get var '##core#macro-alias) symbol? => values)
 	      (else var)))
 
       (define (lookup var0 e)