diff --git a/ChangeLog b/ChangeLog
index 3942ac876b..4603026bcc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,18 @@
-Wed Sep 13 17:11:19 2000  Yukihiro Matsumoto  <matz@ruby-lang.org>
+Mon Sep 18 17:46:11 2000  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* stable version 1.6.0 released.
 
+Sat Sep 16 03:29:59 2000  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* eval.c (rb_f_require): rb_provided() called too early; does not
+	  work well with threads.
+
+	* parse.y (ensure): should distinguish empty ensure and non
+	  existing ensure.
+
+	* file.c (Init_File): extending File by class of FileTest was
+	  serious mistake.
+
 Thu Sep 14 02:46:54 2000  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* eval.c (rb_thread_yield): array strip should be done in this
diff --git a/eval.c b/eval.c
index f396638013..31270be266 100644
--- a/eval.c
+++ b/eval.c
@@ -5074,8 +5074,6 @@ rb_f_require(obj, fname)
     volatile int safe = ruby_safe_level;
 
     Check_SafeStr(fname);
-    if (rb_provided(RSTRING(fname)->ptr)) return Qfalse;
-
     ext = strrchr(RSTRING(fname)->ptr, '.');
     if (ext) {
 	if (strcmp(".rb", ext) == 0) {
diff --git a/file.c b/file.c
index 5c4dcaec01..00f4f2c15b 100644
--- a/file.c
+++ b/file.c
@@ -2153,40 +2153,47 @@ rb_find_file(file)
     return 0;
 }
 
-void
+static void
+define_filetest_function(name, func, argc)
+    const char *name;
+    VALUE (*func)();
+    int argc;
+{
+    rb_define_module_function(rb_mFileTest, name, func, argc);
+    rb_define_singleton_method(rb_cFile, name, func, argc);
+}
+
 Init_File()
 {
     rb_mFileTest = rb_define_module("FileTest");
-
-    rb_define_module_function(rb_mFileTest, "directory?",  test_d, 1);
-    rb_define_module_function(rb_mFileTest, "exist?",  test_e, 1);
-    rb_define_module_function(rb_mFileTest, "exists?",  test_e, 1); /* temporary */
-    rb_define_module_function(rb_mFileTest, "readable?",  test_r, 1);
-    rb_define_module_function(rb_mFileTest, "readable_real?",  test_R, 1);
-    rb_define_module_function(rb_mFileTest, "writable?",  test_w, 1);
-    rb_define_module_function(rb_mFileTest, "writable_real?",  test_W, 1);
-    rb_define_module_function(rb_mFileTest, "executable?",  test_x, 1);
-    rb_define_module_function(rb_mFileTest, "executable_real?",  test_X, 1);
-    rb_define_module_function(rb_mFileTest, "file?",  test_f, 1);
-    rb_define_module_function(rb_mFileTest, "zero?",  test_z, 1);
-    rb_define_module_function(rb_mFileTest, "size?",  test_s, 1);
-    rb_define_module_function(rb_mFileTest, "size",   test_s, 1);
-    rb_define_module_function(rb_mFileTest, "owned?",  test_owned, 1);
-    rb_define_module_function(rb_mFileTest, "grpowned?",  test_grpowned, 1);
-
-    rb_define_module_function(rb_mFileTest, "pipe?",  test_p, 1);
-    rb_define_module_function(rb_mFileTest, "symlink?",  test_l, 1);
-    rb_define_module_function(rb_mFileTest, "socket?",  test_S, 1);
-
-    rb_define_module_function(rb_mFileTest, "blockdev?",  test_b, 1);
-    rb_define_module_function(rb_mFileTest, "chardev?",  test_c, 1);
-
-    rb_define_module_function(rb_mFileTest, "setuid?",  test_suid, 1);
-    rb_define_module_function(rb_mFileTest, "setgid?",  test_sgid, 1);
-    rb_define_module_function(rb_mFileTest, "sticky?",  test_sticky, 1);
-
     rb_cFile = rb_define_class("File", rb_cIO);
-    rb_extend_object(rb_cFile, CLASS_OF(rb_mFileTest));
+
+    define_filetest_function("directory?", test_d, 1);
+    define_filetest_function("exist?", test_e, 1);
+    define_filetest_function("exists?", test_e, 1); /* temporary */
+    define_filetest_function("readable?", test_r, 1);
+    define_filetest_function("readable_real?", test_R, 1);
+    define_filetest_function("writable?", test_w, 1);
+    define_filetest_function("writable_real?", test_W, 1);
+    define_filetest_function("executable?", test_x, 1);
+    define_filetest_function("executable_real?", test_X, 1);
+    define_filetest_function("file?", test_f, 1);
+    define_filetest_function("zero?", test_z, 1);
+    define_filetest_function("size?", test_s, 1);
+    define_filetest_function("size", test_s, 1);
+    define_filetest_function("owned?", test_owned, 1);
+    define_filetest_function("grpowned?", test_grpowned, 1);
+
+    define_filetest_function("pipe?", test_p, 1);
+    define_filetest_function("symlink?", test_l, 1);
+    define_filetest_function("socket?", test_S, 1);
+
+    define_filetest_function("blockdev?", test_b, 1);
+    define_filetest_function("chardev?", test_c, 1);
+
+    define_filetest_function("setuid?", test_suid, 1);
+    define_filetest_function("setgid?", test_sgid, 1);
+    define_filetest_function("sticky?", test_sticky, 1);
 
     rb_define_singleton_method(rb_cFile, "stat",  rb_file_s_stat, 1);
     rb_define_singleton_method(rb_cFile, "lstat", rb_file_s_lstat, 1);
diff --git a/parse.y b/parse.y
index 3a273da94e..39ac6f6f60 100644
--- a/parse.y
+++ b/parse.y
@@ -1507,7 +1507,11 @@ rescue		: kRESCUE exc_list exc_var then
 ensure		: none
 		| kENSURE compstmt
 		    {
-			$$ = $2;
+			if ($2)
+			    $$ = $2;
+			else
+			    /* place holder */
+			    $$ = NEW_NIL();
 		    }
 
 literal		: numeric
diff --git a/version.h b/version.h
index 09edb15a5b..12b6097c31 100644
--- a/version.h
+++ b/version.h
@@ -1,4 +1,4 @@
 #define RUBY_VERSION "1.6.0"
-#define RUBY_RELEASE_DATE "2000-09-12"
+#define RUBY_RELEASE_DATE "2000-09-18"
 #define RUBY_VERSION_CODE 160
-#define RUBY_RELEASE_CODE 20000912
+#define RUBY_RELEASE_CODE 20000918