1 files changed, 3 insertions, 3 deletions
diff --git a/io.c b/io.c
index ddd9f1a9ff..62a948093d 100644
--- a/io.c
+++ b/io.c
@@ -5194,9 +5194,9 @@ rb_io_extract_encoding_option(VALUE opt, rb_encoding **enc_p, rb_encoding **enc2
     if ((extenc != Qundef || intenc != Qundef) && !NIL_P(encoding)) {
 	if (!NIL_P(ruby_verbose)) {
 	    int idx = rb_to_encoding_index(encoding);
-	    rb_warn("Ignoring encoding parameter '%s': %s_encoding is used",
-		    idx < 0 ? StringValueCStr(encoding) : rb_enc_name(rb_enc_from_index(idx)),
-		    extenc == Qundef ? "internal" : "external");
+	    if (idx >= 0) encoding = rb_enc_from_encoding(rb_enc_from_index(idx));
+	    rb_warn("Ignoring encoding parameter '%"PRIsVALUE"': %s_encoding is used",
+		    encoding, extenc == Qundef ? "internal" : "external");
 	}
 	encoding = Qnil;
     }