diff --git a/mmap_ninja/pyproject.toml b/mmap_ninja/pyproject.toml
index 3dbda9d..ff5ba5e 100644
--- a/mmap_ninja/pyproject.toml
+++ b/mmap_ninja/pyproject.toml
@@ -32,3 +32,4 @@ Homepage = "https://github.com/hristo-vrigazov/mmap.ninja"
 
 [project.optional-dependencies]
 dev = ["pytest", "tqdm", "pytest-dotenv"]
+parallel = ["joblib"]