diff --git a/ChangeLog b/ChangeLog
index 17220f5ae5..8a8ac966ff 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu May 29 22:41:48 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* io.c (argf_readchar): raise EOFError, synchronizing IO#readchar.
+
 Thu May 29 22:29:39 2008  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* io.c (argf_external_encoding, argf_internal_encoding): fix SEGV by
diff --git a/io.c b/io.c
index e4a0c21c19..6e7e549dd9 100644
--- a/io.c
+++ b/io.c
@@ -7193,7 +7193,7 @@ argf_readchar(VALUE argf)
     VALUE ch;
 
   retry:
-    if (!next_argv()) return Qnil;
+    if (!next_argv()) return rb_eof_error();
     if (TYPE(current_file) != T_FILE) {
 	ch = rb_funcall3(current_file, rb_intern("getc"), 0, 0);
     }