diff --git a/glotaran/analysis/optimize.py b/glotaran/analysis/optimize.py
index 585e308b6..92a6cac97 100644
--- a/glotaran/analysis/optimize.py
+++ b/glotaran/analysis/optimize.py
@@ -100,8 +100,7 @@ def _calculate_penalty(
 
     penalties = [group.full_penalty for group in optimization_groups]
 
-    penalty = np.concatenate(penalties) if len(penalties) != 1 else penalties[0]
-    return penalty
+    return np.concatenate(penalties) if len(penalties) != 1 else penalties[0]
 
 
 def _create_result(
diff --git a/glotaran/test/test_spectral_penalties.py b/glotaran/test/test_spectral_penalties.py
index 0f8f5f289..6bebb8075 100644
--- a/glotaran/test/test_spectral_penalties.py
+++ b/glotaran/test/test_spectral_penalties.py
@@ -216,8 +216,7 @@ def test_equal_area_penalties(debug=False):
     # for both we perturb kinetic parameters a bit to give the optimizer some work
     pspec_wp = dict(deepcopy(pspec.base), **pspec.equal_area)
     pspec_wp["kinetic"] = [v * 1.01 for v in pspec_wp["kinetic"]]
-    pspec_wp.update({"i": [[1, {"vary": False}], 1]})
-
+    pspec_wp["i"] = [[1, {"vary": False}], 1]
     pspec_np = dict(deepcopy(pspec.base))
 
     param_wp = ParameterGroup.from_dict(pspec_wp)