1 files changed, 2 insertions, 1 deletions
diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index bc0716b835..d2bcf76eb4 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -2747,7 +2747,8 @@ rb_gzwriter_write(VALUE obj, VALUE str)
 {
     struct gzfile *gz = get_gzfile(obj);
 
-    StringValue(str);
+    if (TYPE(str) != T_STRING)
+	str = rb_obj_as_string(str);
     if (gz->enc2 && gz->enc2 != rb_ascii8bit_encoding()) {
 	str = rb_str_conv_enc(str, rb_enc_get(str), gz->enc2);
     }