1 files changed, 8 insertions, 0 deletions
diff --git a/io.c b/io.c
index 5c43a062de..b7a5314983 100644
--- a/io.c
+++ b/io.c
@@ -729,6 +729,14 @@ make_writeconv(rb_io_t *fptr)
                     denc = enc->name;
                     fptr->writeconv_stateless = rb_str_new2(senc);
                 }
+                else if ((fptr->encs.ecflags & ECONV_STATEFUL_ENCODER_MASK) && !rb_enc_asciicompat(enc)) {
+                    /* xxx: stateful encoder works for ASCII compatible encoding.
+                     * So we need to choose an encoding which is ASCII compatible and superset of enc.
+                     * For encodings which is superset of UTF-8, UTF-8 is not appropriate choice.  */
+                    senc = "UTF-8";
+                    denc = enc->name;
+                    fptr->writeconv_stateless = rb_str_new2("UTF-8");
+                }
                 else {
                     senc = denc = "";
                     fptr->writeconv_stateless = rb_str_new2(enc->name);