diff --git a/unitary/alpha/qudit_state_transform.py b/unitary/alpha/qudit_state_transform.py
index abccc4d9..4babc429 100644
--- a/unitary/alpha/qudit_state_transform.py
+++ b/unitary/alpha/qudit_state_transform.py
@@ -39,7 +39,7 @@ def qudit_to_qubit_state(
     qudit_dimension: int,
     num_qudits: int,
     qudit_state_vector: np.ndarray,
-    _pad_value: np.complex_ = 0,
+    _pad_value: np.complex128 = 0,
 ) -> np.ndarray:
     """Converts a qudit-space quantum state vector to m-qubit-per-qudit column vector.
 
diff --git a/unitary/alpha/qudit_state_transform_test.py b/unitary/alpha/qudit_state_transform_test.py
index 5afcbb0b..39eace0e 100644
--- a/unitary/alpha/qudit_state_transform_test.py
+++ b/unitary/alpha/qudit_state_transform_test.py
@@ -85,7 +85,7 @@ def test_qudit_state_and_unitary_transform_equivalence(qudit_dim, num_qudits):
         (
             3,
             2,
-            np.array([1, 0, 0, 0, 0, 0, 0, 0, 1], dtype=np.complex_),
+            np.array([1, 0, 0, 0, 0, 0, 0, 0, 1], dtype=np.complex128),
             np.array(
                 [
                     1,