diff --git a/pyproject.toml b/pyproject.toml
index a0905ee..de62ed0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -28,6 +28,7 @@ dependencies = [
   "numpy",
   "scipy",
   "pennylane",
+  "gast>=0.6,<1",
   "pyscf",
   "basis_set_exchange",
 ]
diff --git a/requirements-validation.txt b/requirements-validation.txt
index c382ae7..5d8a857 100644
--- a/requirements-validation.txt
+++ b/requirements-validation.txt
@@ -4,6 +4,7 @@
 numpy==1.26.4
 scipy==1.14.1
 pennylane==0.44.0
+gast==0.7.0
 pyscf==2.11.0
 basis-set-exchange==0.12
 pytest==9.0.2