diff --git a/ChangeLog b/ChangeLog
index bfaa1f5c02..ed1cbffa0d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Wed Apr 11 13:29:26 2001  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* class.c (rb_singleton_class_attached): should modify iv_tbl by
+	  itself, no longer use rb_iv_set() to avoid freeze check error.
+
+	* variable.c (rb_const_get): error message "uninitialized constant
+	  Foo at Bar::Baz" instead of "uninitialized constantBar::Baz::Foo".
+
 Tue Apr 10 02:24:40 2001  Nobuyoshi Nakada  <nobu.nakada@nifty.ne.jp>
 
 	* io.c (opt_i_set): should strdup() inplace_edit string.
diff --git a/class.c b/class.c
index b76367a77f..b5caf3082a 100644
--- a/class.c
+++ b/class.c
@@ -112,8 +112,12 @@ void
 rb_singleton_class_attached(klass, obj)
     VALUE klass, obj;
 {
-    if (FL_TEST(klass, FL_SINGLETON))
-	rb_iv_set(klass, "__attached__", obj);
+    if (FL_TEST(klass, FL_SINGLETON)) {
+	if (!RCLASS(klass)->iv_tbl) {
+	    RCLASS(klass)->iv_tbl = st_init_numtable();
+	}
+	st_insert(RCLASS(klass)->iv_tbl, rb_intern("__attached__"), obj);
+    }
 }
 
 VALUE
@@ -253,11 +257,6 @@ rb_include_module(klass, module)
     VALUE p;
     int changed = 0;
 
-    rb_frozen_class_p(klass);
-    if (!OBJ_TAINTED(klass)) {
-	rb_secure(4);
-    }
-    
     rb_frozen_class_p(klass);
     if (!OBJ_TAINTED(klass)) {
 	rb_secure(4);
diff --git a/variable.c b/variable.c
index 445f811a18..6e2ef0c875 100644
--- a/variable.c
+++ b/variable.c
@@ -1084,9 +1084,9 @@ rb_const_get(klass, id)
 
     /* Uninitialized constant */
     if (klass && klass != rb_cObject)
-	rb_raise(rb_eNameError, "uninitialized constant %s::%s",
-		 RSTRING(rb_class_path(klass))->ptr,
-		 rb_id2name(id));
+	rb_raise(rb_eNameError, "uninitialized constant %s at %s",
+		 rb_id2name(id),
+		 RSTRING(rb_class_path(klass))->ptr);
     else {
 	rb_raise(rb_eNameError, "uninitialized constant %s",rb_id2name(id));
     }
diff --git a/version.h b/version.h
index 4b32460ba7..bed4533f35 100644
--- a/version.h
+++ b/version.h
@@ -1,4 +1,4 @@
 #define RUBY_VERSION "1.6.4"
-#define RUBY_RELEASE_DATE "2001-04-10"
+#define RUBY_RELEASE_DATE "2001-04-11"
 #define RUBY_VERSION_CODE 164
-#define RUBY_RELEASE_CODE 20010410
+#define RUBY_RELEASE_CODE 20010411