diff --git a/ChangeLog b/ChangeLog
index 14b0601a93..a244e1c625 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Jun 18 01:29:16 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* file.c (file_expand_path): drive letter is ascii only.
+	  [ruby-dev:38612]
+
 Thu Jun 18 01:09:27 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* configure.in (ridir, RI_BASE_NAME): fixed for path expansion.
diff --git a/file.c b/file.c
index 41080ff238..0b1eef2a79 100644
--- a/file.c
+++ b/file.c
@@ -2745,6 +2745,7 @@ file_expand_path(VALUE fname, VALUE dname, int abs_mode, VALUE result)
 	    memcpy(p, s, 2);
 	    p += 2;
 	    s += 2;
+	    rb_enc_associate_index(result, rb_usascii_encindex());
 	}
 	else {
 	    /* specified drive, but not full path */