diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5186912..1cb562b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [4.0.2] - 2021-06-11
 ### Fixed
 - Wait until container's ports are available before considering it created
+- Fix installation by explicitly including six as a dependency
 
 ## [4.0.0] - 2021-03-03
 ### Changed
diff --git a/pyproject.toml b/pyproject.toml
index 9910d5c..9b45de8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,6 +19,9 @@ pytest = ">=5.0"
 requests = ">=2.22.0"
 docker = ">=4.2.0"
 typing_extensions = ">=3.7.4"
+# docker==5.0 needs six but doesn't require it as a dependency
+# https://github.com/docker/docker-py/issues/2842
+six = ">=1.15.0"
 
 [tool.poetry.dev-dependencies]
 flake8 = ">=3.7.7"