diff --git a/pyproject.toml b/pyproject.toml
index a7e5b42..899614b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -57,12 +57,14 @@ tqdm = "^4.64.1"
 auxiliary = "^0.0.41"
 rich = "^13.6.0"
 
-
+# optional registration backends
 antspyx = { version = "^0.4.2", optional = true }
 
 [tool.poetry.extras]
+all = ["antspyx"]
 ants = ["antspyx"]
 
+
 [tool.poetry.dev-dependencies]
 pytest = "^6.2"