1 files changed, 20 insertions, 1 deletions
diff --git a/io.c b/io.c
index 472957f598..ce0c35048b 100644
--- a/io.c
+++ b/io.c
@@ -4885,7 +4885,26 @@ rb_scan_open_args(int argc, VALUE *argv,
     opt = pop_last_hash(&argc, argv);
     rb_scan_args(argc, argv, "12", &fname, &vmode, &vperm);
     FilePathValue(fname);
-
+#if defined _WIN32 || defined __APPLE__
+    {
+	static rb_encoding *fs_encoding;
+	rb_encoding *fname_encoding = rb_enc_get(fname);
+	if (!fs_encoding)
+	    fs_encoding = rb_filesystem_encoding();
+	if (rb_usascii_encoding() != fname_encoding
+	    && rb_ascii8bit_encoding() != fname_encoding
+#if defined __APPLE__
+	    && rb_utf8_encoding() != fname_encoding
+#endif
+	    && fs_encoding != fname_encoding) {
+	    static VALUE fs_enc;
+	    if (!fs_enc)
+		fs_enc = rb_enc_from_encoding(fs_encoding);
+	    fname = rb_str_encode(fname, fs_enc, 0, Qnil);
+	}
+    }
+#endif
+ 
     rb_io_extract_modeenc(&vmode, &vperm, opt, &oflags, &fmode, convconfig_p);
 
     perm = NIL_P(vperm) ? 0666 :  NUM2UINT(vperm);