diff --git a/ChangeLog b/ChangeLog
index 4ea3f8f64d..3b41bda559 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -45,6 +45,11 @@ Tue Sep 30 23:00:05 2008  Yuki Sonoda (Yugui)  <yugui@yugui.jp>
 
 	* lib/test/unit/testcase.rb: ditto.
 
+Tue Sep 30 20:17:26 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* io.c (rb_io_extract_modeenc): should honor value of the
+	  textmode: and binmode: options.
+
 Tue Sep 30 17:04:59 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* test/bigdecimal/test_bigdecimal.rb (test_sqrt_bigdecimal): wrong
diff --git a/io.c b/io.c
index 774f3e7e18..7985aebd7f 100644
--- a/io.c
+++ b/io.c
@@ -3922,10 +3922,10 @@ rb_io_extract_modeenc(VALUE *vmode_p, VALUE *vperm_p, VALUE opthash,
     else {
 	VALUE v;
 	v = rb_hash_aref(opthash, sym_textmode);
-	if (!NIL_P(v))
+	if (!NIL_P(v) && RTEST(v))
             fmode |= FMODE_TEXTMODE;
 	v = rb_hash_aref(opthash, sym_binmode);
-	if (!NIL_P(v)) {
+	if (!NIL_P(v) && RTEST(v)) {
             fmode |= FMODE_BINMODE;
 #ifdef O_BINARY
             oflags |= O_BINARY;