ext/json/ext/parser/parser.rl in json_pure-2.0.1 vs ext/json/ext/parser/parser.rl in json_pure-2.0.2

@@ -563,9 +563,12 @@
 static VALUE convert_encoding(VALUE source)
 {
 #ifdef HAVE_RUBY_ENCODING_H
   rb_encoding *enc = rb_enc_get(source);
   if (enc == rb_ascii8bit_encoding()) {
+    if (OBJ_FROZEN(source)) {
+      source = rb_str_dup(source);
+    }
     FORCE_UTF8(source);
   } else {
     source = rb_str_conv_enc(source, NULL, rb_utf8_encoding());
   }
 #endif