diff --git a/src/scgenerator/noise.py b/src/scgenerator/noise.py
index feee016..e8475ca 100644
--- a/src/scgenerator/noise.py
+++ b/src/scgenerator/noise.py
@@ -16,6 +16,7 @@ class NoiseMeasurement:
     psd: np.ndarray
     phase: np.ndarray | None = None
     psd_interp: interp1d = field(init=False)
+    rng: np.random.Generator = field(default_factory=np.random.default_rng)
     _window_functions: ClassVar[dict[str, Callable[[int], np.ndarray]]] = {}
 
     @classmethod
@@ -190,7 +191,7 @@ class NoiseMeasurement:
 
         freq, spec = self.sample_spectrum(nt, dt)
         if phase is None:
-            phase = 2 * np.pi * np.random.rand(len(freq))
+            phase = 2 * np.pi * self.rng.random(len(freq))
         time, dt = math.irfftfreq(freq, True)
 
         amp = np.sqrt(spec) * np.exp(1j * phase)
diff --git a/src/scgenerator/spectra.py b/src/scgenerator/spectra.py
index fd28f37..e2bda18 100644
--- a/src/scgenerator/spectra.py
+++ b/src/scgenerator/spectra.py
@@ -332,7 +332,7 @@ def _bundle_external_files(params: Parameters, io: PropagationIOHandler):
     existing_files = set(io.keys())
     for _, value in params.items():
         if isinstance(value, DataFile):
-            data = value.load_data()
+            data = value.load_bytes()
 
             value.io = io
             value.prefix = "zip"