Add another missing dependency.
diff --git a/pubspec.yaml b/pubspec.yaml
index c37dda6..651dbec 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -8,6 +8,7 @@
 
 dependencies:
   path: ^1.6.4
+  charcode: ^1.1.0
 
 dev_dependencies:
   test: ^1.6.4