diff --git a/src/nomad_simulations/model_system.py b/src/nomad_simulations/model_system.py
index a1acaed8..6426b332 100644
--- a/src/nomad_simulations/model_system.py
+++ b/src/nomad_simulations/model_system.py
@@ -453,8 +453,8 @@ def __init__(
         self.combo = combo
         self.type = type
 
-        counts, self.bins = np.histogram(distribution_values.magnitude, bins=bins)
-        self.bins *= distribution_values.u
+        counts, _bins = np.histogram(distribution_values.magnitude, bins=bins)
+        self.bins = _bins * distribution_values.u
         # normalize so the minimum is 1
         if len(nonzero_counts := counts[np.where(counts > 0)]):
             self.frequency = counts / np.min(nonzero_counts)