diff --git a/lib/init-7.scm b/lib/init-7.scm
index 3472642e..035bb36c 100644
--- a/lib/init-7.scm
+++ b/lib/init-7.scm
@@ -60,19 +60,27 @@
   (define (map1 proc ls res)
     (if (pair? ls)
         (map1 proc (cdr ls) (cons (proc (car ls)) res))
-        (reverse res)))
+        (if (null? ls)
+            (reverse res)
+            (error "map: improper list" ls))))
   (define (mapn proc lol res)
     (if (every pair? lol)
         (mapn proc
               (map1 cdr lol '())
               (cons (apply proc (map1 car lol '())) res))
-        (reverse res)))
+        (if (every (lambda (x) (if (null? x) #t (pair? x))) lol)
+            (reverse res)
+            (error "map: improper list" ls))))
   (if (null? lol)
       (map1 proc ls '())
       (mapn proc (cons ls lol) '())))
 
 (define (for-each f ls . lol)
-  (define (for1 f ls) (if (pair? ls) (begin (f (car ls)) (for1 f (cdr ls)))))
+  (define (for1 f ls)
+    (if (pair? ls)
+        (begin (f (car ls)) (for1 f (cdr ls)))
+        (if (not (null? ls))
+            (error "for-each: improper list" ls))))
   (if (null? lol) (for1 f ls) (begin (apply map f ls lol) (if #f #f))))
 
 (define (any pred ls . lol)