diff --git a/ChangeLog b/ChangeLog
index 17d2f7a5c2..cad39ba42f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Aug 29 02:45:29 2008  Tanaka Akira  <akr@fsij.org>
+
+	* transcode.c (econv_convert): new method.
+
 Fri Aug 29 02:38:14 2008  Tanaka Akira  <akr@fsij.org>
 
 	* transcode.c (econv_primitive_convert): accept nil as
diff --git a/test/ruby/test_econv.rb b/test/ruby/test_econv.rb
index 7d6e78227b..8f29fb9f31 100644
--- a/test/ruby/test_econv.rb
+++ b/test/ruby/test_econv.rb
@@ -559,4 +559,13 @@ class TestEncodingConverter < Test::Unit::TestCase
     assert_equal(:finished, ret)
     assert_equal(["xyzabc", ""], [dst, src])
   end
+
+  def test_convert
+    ec = Encoding::Converter.new("utf-8", "euc-jp")
+    assert_raise(Encoding::InvalidByteSequence) { ec.convert("a\x80") }
+    assert_raise(Encoding::ConversionUndefined) { ec.convert("\ufffd") }
+    ret = ec.primitive_convert(nil, "", nil, nil)
+    assert_equal(:finished, ret)
+    assert_raise(ArgumentError) { ec.convert("a") }
+  end
 end
diff --git a/transcode.c b/transcode.c
index 52c6d27ef8..79450a43ae 100644
--- a/transcode.c
+++ b/transcode.c
@@ -2491,6 +2491,59 @@ econv_primitive_convert(int argc, VALUE *argv, VALUE self)
     return econv_result_to_symbol(res);
 }
 
+/*
+ * call-seq:
+ *   convert(source_string) -> destination_string
+ *
+ * convert source_string and return destination_string.
+ *
+ * source_string is assumed as a part of source.
+ * i.e.  Encoding::Converter::PARTIAL_INPUT is used internally.
+ *
+ * If a conversion error occur,
+ * Encoding::ConversionUndefined or
+ * Encoding::InvalidByteSequence is raised.
+ *
+ */
+static VALUE
+econv_convert(VALUE self, VALUE source_string)
+{
+    VALUE ret, dst;
+    VALUE av[5];
+    int ac;
+    rb_econv_t *ec = check_econv(self);
+
+    StringValue(source_string);
+
+    dst = rb_str_new(NULL, 0);
+
+    av[0] = rb_str_dup(source_string);
+    av[1] = dst;
+    av[2] = Qnil;
+    av[3] = Qnil;
+    av[4] = INT2NUM(ECONV_PARTIAL_INPUT);
+    ac = 5;
+
+    ret = econv_primitive_convert(ac, av, self);
+
+    if (ret == sym_invalid_byte_sequence ||
+        ret == sym_undefined_conversion ||
+        ret == sym_incomplete_input) {
+        VALUE exc = make_econv_exception(ec);
+        rb_exc_raise(exc);
+    }
+
+    if (ret == sym_finished) {
+        rb_raise(rb_eArgError, "converter already finished");
+    }
+
+    if (ret != sym_source_buffer_empty) {
+        rb_bug("unexpected result of econv_primitive_convert");
+    }
+
+    return dst;
+}
+
 /*
  * call-seq:
  *   primitive_errinfo -> array
@@ -2721,6 +2774,7 @@ Init_transcode(void)
     rb_define_method(rb_cEncodingConverter, "source_encoding", econv_source_encoding, 0);
     rb_define_method(rb_cEncodingConverter, "destination_encoding", econv_destination_encoding, 0);
     rb_define_method(rb_cEncodingConverter, "primitive_convert", econv_primitive_convert, -1);
+    rb_define_method(rb_cEncodingConverter, "convert", econv_convert, 1);
     rb_define_method(rb_cEncodingConverter, "primitive_errinfo", econv_primitive_errinfo, 0);
     rb_define_method(rb_cEncodingConverter, "primitive_insert_output", econv_primitive_insert_output, 1);
     rb_define_method(rb_cEncodingConverter, "primitive_putback", econv_primitive_putback, 1);