diff --git a/pyproject.toml b/pyproject.toml
index 99d4b197..bfdc0f32 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "diagrams"
-version = "0.2.3"
+version = "0.2.4"
 description = "Diagram as Code"
 license = "MIT"
 authors = ["mingrammer <mingrammer@gmail.com>"]
@@ -13,6 +13,7 @@ include = ["resources/**/*"]
 python = "^3.6"
 graphviz = "^0.13.2"
 jinja2 = "^2.10"
+contextvars = { version = "^2.4", python = "~3.6" }
 
 [tool.poetry.dev-dependencies]
 pytest = "^3.0"