diff --git a/pyproject.toml b/pyproject.toml
index 773b662c..83d19a59 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -25,6 +25,7 @@ dependencies = [
 dynamic = [
     "version",
 ]
+requires-python = "3.10"
 
 [project.readme]
 file = "README.md"
@@ -40,7 +41,7 @@ repository = "https://github.com/spacetelescope/pysiaf"
 
 [project.optional-dependencies]
 test = [
-    'pytest',
+    "pytest",
 ]
 docs = [
     "stsci-rtd-theme",