3 files changed, 15 insertions, 4 deletions
diff --git a/ChangeLog b/ChangeLog
index 24f4f8d2..1f64592f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2012-01-27  Kaz Kylheku  <kaz@kylheku.com>
+
+	* hash.c (hash_begin): Missing type check added, otherwise
+	passing in an object that is not a hash results in corruption
+	or crashing behavior.
+
+	* lib.c (class_check): Improved to a one-step check with a clear
+	message.
+
 2012-01-26  Kaz Kylheku  <kaz@kylheku.com>
 
 	Version 55
diff --git a/hash.c b/hash.c
index e03664cd..e8f5bb1b 100644
--- a/hash.c
+++ b/hash.c
@@ -389,7 +389,10 @@ static struct cobj_ops hash_iter_ops = {
 val hash_begin(val hash)
 {
   val hi_obj;
-  struct hash_iter *hi = (struct hash_iter *) chk_malloc(sizeof *hi);
+  struct hash_iter *hi;
+  class_check (hash, hash_s);
+
+  hi = (struct hash_iter *) chk_malloc(sizeof *hi);
   hi->hash = nil;
   hi->chain = -1;
   hi->cons = nil;
diff --git a/lib.c b/lib.c
index 881d2c0c..0aedac3f 100644
--- a/lib.c
+++ b/lib.c
@@ -169,9 +169,8 @@ val type_check3(val obj, int t1, int t2, int t3)
 
 val class_check(val cobj, val class_sym)
 {
-  type_check (cobj, COBJ);
-  type_assert (cobj->co.cls == class_sym, (lit("~a is not a cobj of class ~a"),
-                                           cobj, class_sym));
+  type_assert (cobj && cobj->t.type == COBJ && cobj->co.cls == class_sym, 
+               (lit("~a is not of type ~a"), cobj, class_sym, nao));
   return t;
 }