diff --git a/opencl_fdtd/test_simulation.py b/opencl_fdtd/test_simulation.py
index c68a2cf..9c8649a 100644
--- a/opencl_fdtd/test_simulation.py
+++ b/opencl_fdtd/test_simulation.py
@@ -323,8 +323,9 @@ class JdotE_3DUniformDX(unittest.TestCase):
         self.epsilon = numpy.full(shape, 4, dtype=float)
         self.epsilon[self.src_mask] = 2
 
-        e = numpy.random.randint(-128, 128 + 1, size=shape).astype(float)
-        h = numpy.random.randint(-128, 128 + 1, size=shape).astype(float)
+        rng = numpy.random.default_rng()
+        e = rng.integers(-128, 128 + 1, size=shape, dtype=float)
+        h = rng.integers(-128, 128 + 1, size=shape, dtype=float)
         self.es = [e]
         self.hs = [h]
         self.ss = []