diff --git a/src/sid/contacts.py b/src/sid/contacts.py
index 299eea1c..aa08c6d1 100644
--- a/src/sid/contacts.py
+++ b/src/sid/contacts.py
@@ -621,28 +621,30 @@ def post_process_contacts(contacts, states, contact_models):
     contacts.loc[has_no_contacts, recurrent_models] = False
 
     if random_models:
-        random_contacts = contacts[random_models]
-
-        integers = random_contacts.select_dtypes(include=np.integer).columns.tolist()
+        integers = (
+            contacts[random_models].select_dtypes(include=np.integer).columns.tolist()
+        )
         if integers:
-            random_contacts[integers] = random_contacts[integers].astype(
-                DTYPE_N_CONTACTS
-            )
+            contacts[integers] = contacts[integers].astype(DTYPE_N_CONTACTS)
 
-        floats = random_contacts.select_dtypes(include=np.floating).columns.tolist()
-        if floats:
-            random_contacts[floats] = random_contacts[floats].apply(
-                lambda x: _sum_preserving_round(x.to_numpy()).astype(DTYPE_N_CONTACTS)
-            )
+        floats = (
+            contacts[random_models].select_dtypes(include=np.floating).columns.tolist()
+        )
+        for float_col in floats:
+            contacts.loc[:, float_col] = _sum_preserving_round(
+                contacts[float_col].to_numpy()
+            ).astype(DTYPE_N_CONTACTS)
 
-        no_integers = random_contacts.select_dtypes(exclude=np.integer).columns.tolist()
+        no_integers = (
+            contacts[random_models].select_dtypes(exclude=np.integer).columns.tolist()
+        )
         if no_integers:
-            dtype_mapping = random_contacts[no_integers].dtypes.to_dict()
+            dtype_mapping = contacts[no_integers].dtypes.to_dict()
             raise ValueError(
                 "The following contacts should be integers or floats, but they have a "
                 f"different dtype.\n\n{dtype_mapping}"
             )
-
+        random_contacts = contacts[random_models]
     else:
         random_contacts = None