diff --git a/src/lbmpy/flow_statistics.py b/src/lbmpy/flow_statistics.py
index 4b13866a1267016f7c3ee8c9f2c69dc23d8ab663..6d5433b21c297ed7e53176359a8266e628c4f064 100644
--- a/src/lbmpy/flow_statistics.py
+++ b/src/lbmpy/flow_statistics.py
@@ -69,8 +69,8 @@ def welford_assignments(field, mean_field, sum_of_products_field=None):
 
     if sum_of_products_field is not None:
         delta2 = sp.symbols(f"delta2_:{dim}")
-        main_assignments.append(ps.Assignment(delta2[i], welford_field.at_index(i) - welford_mean_field.at_index(i)))
         for i in range(dim):
+            main_assignments.append(ps.Assignment(delta2[i], welford_field.at_index(i) - welford_mean_field.at_index(i)))
             for j in range(dim):
                 idx = i * dim + j
                 main_assignments.append(ps.Assignment(