diff --git a/tests/test_parabolic_profile.py b/tests/test_parabolic_profile.py
index ebd0859..ba0a095 100644
--- a/tests/test_parabolic_profile.py
+++ b/tests/test_parabolic_profile.py
@@ -55,8 +55,8 @@ def parabolic_coefficient(z):
     # Create identical bunches for each case.
     bunch = get_matched_bunch(
         1e-6, 1e-6, 200, 1, 3, laser.xi_c - 30e-6, 1e-6, 1e4, n_p=n_p)
-    bunch_1 = deepcopy(bunch)
-    bunch_2 = deepcopy(bunch)
+    bunch_1 = bunch.copy()
+    bunch_2 = bunch.copy()
 
     # Create single plasma stage (containing all sections).
     plasma_single = PlasmaStage(