diff --git a/tests/test_boundary.py b/tests/test_boundary.py
index 631e488..2554d0a 100644
--- a/tests/test_boundary.py
+++ b/tests/test_boundary.py
@@ -8,6 +8,7 @@
 from test_geometry import read_sdf
 from schism import BoundaryConditions, Boundary, BoundaryGeometry
 from collections import Counter
+from devito.tools.utils import filter_sorted
 
 
 class TestSubstitutions:
@@ -140,5 +141,9 @@ def test_forward_timestep(self, s_o):
         current_weights = dv.symbolics.retrieve_functions(current)
         forward_weights = dv.symbolics.retrieve_functions(forward)
 
+        # Sort to ensure that weights are in the same order
+        current_weights = filter_sorted(current_weights)
+        forward_weights = filter_sorted(forward_weights)
+
         for crt, fwd in zip(current_weights, forward_weights):
             assert np.all(np.isclose(crt.data, fwd.data))
diff --git a/tests/test_boundary_conditions.py b/tests/test_boundary_conditions.py
index 6eea1b9..6576e21 100644
--- a/tests/test_boundary_conditions.py
+++ b/tests/test_boundary_conditions.py
@@ -245,10 +245,13 @@ def test_coefficient_replacement(self, bc, funcs):
         condition = SingleCondition(bc, funcs=funcs)
         # Check that if we substitute the placeholders for their expressions,
         # we get our original LHS
-        check = sp.simplify(condition.lhs
-                            - condition._mod_lhs.subs(condition.expr_map))
 
-        assert check == 0
+        # Force expansion as sympy as need to string check
+        reconstruction = sp.expand(condition._mod_lhs.subs(condition.expr_map))
+        expanded_lhs = sp.expand(condition.lhs)
+
+        # Matching strings is ugly, but SymPy simplification is unreliable
+        assert str(reconstruction) == str(expanded_lhs)
 
     @pytest.mark.parametrize('bc, g', [(dv.Eq(f+g), g), (dv.Eq(g*f.dx+g), g),
                                        (dv.Eq(f+g+1), g), (dv.Eq(g*(f+1)), g)])
diff --git a/tests/test_substitution.py b/tests/test_substitution.py
index abbd2a9..4c1e5d0 100644
--- a/tests/test_substitution.py
+++ b/tests/test_substitution.py
@@ -257,27 +257,27 @@ def test_fill_weights_consistency(self):
     def test_returned_expr(self):
         """Check that the correct expression is returned"""
         subs = weights_test_setup()
-        ans = 'f(t, x, y)*w_f_f_dy2_0_0(x, y) ' \
-            + '+ f(t, x, y - 2*h_y)*w_f_f_dy2_0_m2(x, y) ' \
-            + '+ f(t, x, y - h_y)*w_f_f_dy2_0_m1(x, y) ' \
-            + '+ f(t, x, y + h_y)*w_f_f_dy2_0_1(x, y) ' \
-            + '+ f(t, x, y + 2*h_y)*w_f_f_dy2_0_2(x, y) ' \
-            + '+ f(t, x - 2*h_x, y)*w_f_f_dy2_m2_0(x, y) ' \
-            + '+ f(t, x - 2*h_x, y - h_y)*w_f_f_dy2_m2_m1(x, y) ' \
-            + '+ f(t, x - 2*h_x, y + h_y)*w_f_f_dy2_m2_1(x, y) ' \
-            + '+ f(t, x - h_x, y)*w_f_f_dy2_m1_0(x, y) ' \
-            + '+ f(t, x - h_x, y - 2*h_y)*w_f_f_dy2_m1_m2(x, y) ' \
-            + '+ f(t, x - h_x, y - h_y)*w_f_f_dy2_m1_m1(x, y) ' \
-            + '+ f(t, x - h_x, y + h_y)*w_f_f_dy2_m1_1(x, y) ' \
-            + '+ f(t, x - h_x, y + 2*h_y)*w_f_f_dy2_m1_2(x, y) ' \
-            + '+ f(t, x + h_x, y)*w_f_f_dy2_1_0(x, y) ' \
-            + '+ f(t, x + h_x, y - 2*h_y)*w_f_f_dy2_1_m2(x, y) ' \
-            + '+ f(t, x + h_x, y - h_y)*w_f_f_dy2_1_m1(x, y) ' \
-            + '+ f(t, x + h_x, y + h_y)*w_f_f_dy2_1_1(x, y) ' \
-            + '+ f(t, x + h_x, y + 2*h_y)*w_f_f_dy2_1_2(x, y) ' \
-            + '+ f(t, x + 2*h_x, y)*w_f_f_dy2_2_0(x, y) ' \
-            + '+ f(t, x + 2*h_x, y - h_y)*w_f_f_dy2_2_m1(x, y) ' \
-            + '+ f(t, x + 2*h_x, y + h_y)*w_f_f_dy2_2_1(x, y)'
+        ans = 'w_f_f_dy2_0_0(x, y)*f(t, x, y) ' \
+            + '+ w_f_f_dy2_0_1(x, y)*f(t, x, y + h_y) ' \
+            + '+ w_f_f_dy2_0_2(x, y)*f(t, x, y + 2*h_y) ' \
+            + '+ w_f_f_dy2_0_m1(x, y)*f(t, x, y - h_y) ' \
+            + '+ w_f_f_dy2_0_m2(x, y)*f(t, x, y - 2*h_y) ' \
+            + '+ w_f_f_dy2_1_0(x, y)*f(t, x + h_x, y) ' \
+            + '+ w_f_f_dy2_1_1(x, y)*f(t, x + h_x, y + h_y) ' \
+            + '+ w_f_f_dy2_1_2(x, y)*f(t, x + h_x, y + 2*h_y) ' \
+            + '+ w_f_f_dy2_1_m1(x, y)*f(t, x + h_x, y - h_y) ' \
+            + '+ w_f_f_dy2_1_m2(x, y)*f(t, x + h_x, y - 2*h_y) ' \
+            + '+ w_f_f_dy2_2_0(x, y)*f(t, x + 2*h_x, y) ' \
+            + '+ w_f_f_dy2_2_1(x, y)*f(t, x + 2*h_x, y + h_y) ' \
+            + '+ w_f_f_dy2_2_m1(x, y)*f(t, x + 2*h_x, y - h_y) ' \
+            + '+ w_f_f_dy2_m1_0(x, y)*f(t, x - h_x, y) ' \
+            + '+ w_f_f_dy2_m1_1(x, y)*f(t, x - h_x, y + h_y) ' \
+            + '+ w_f_f_dy2_m1_2(x, y)*f(t, x - h_x, y + 2*h_y) ' \
+            + '+ w_f_f_dy2_m1_m1(x, y)*f(t, x - h_x, y - h_y) ' \
+            + '+ w_f_f_dy2_m1_m2(x, y)*f(t, x - h_x, y - 2*h_y) ' \
+            + '+ w_f_f_dy2_m2_0(x, y)*f(t, x - 2*h_x, y) ' \
+            + '+ w_f_f_dy2_m2_1(x, y)*f(t, x - 2*h_x, y + h_y) ' \
+            + '+ w_f_f_dy2_m2_m1(x, y)*f(t, x - 2*h_x, y - h_y)'
 
         assert str(subs.expr) == ans