diff --git a/lib/char_reader.dart b/lib/char_reader.dart
index 0f3bf98..ff3a3f1 100644
--- a/lib/char_reader.dart
+++ b/lib/char_reader.dart
@@ -60,6 +60,6 @@
     }
     
     int end = peek() == _EOF ? _source.length : _i;
-    return _source.slice(start, end);
+    return _source.substring(start, end);
   }
 }
\ No newline at end of file