diff --git a/modelx/core/model.py b/modelx/core/model.py
index 8c0e8ec..beea8bf 100644
--- a/modelx/core/model.py
+++ b/modelx/core/model.py
@@ -1437,8 +1437,9 @@ def change_cells_formula(self, cells, func):
         define = True
         for space in self._get_subs(cells.parent, skip_self=False):
             c = space.cells[cells.name]
-            if c is not cells and c.is_defined():
-                break   # Stop when sub cells is defined
+            if (c is not cells and c.is_defined() and
+                    self.get_deriv_bases(c, defined_only=True)[0] is cells):
+                continue   # Skip when c's base is not cells
             space.clear_subs_rootitems()
             space.cells[cells.name].on_change_formula(func, define)
             define = False  # Do not define derived cells
diff --git a/modelx/tests/core/cells/test_formula.py b/modelx/tests/core/cells/test_formula.py
index 9ba60b8..3a630bd 100644
--- a/modelx/tests/core/cells/test_formula.py
+++ b/modelx/tests/core/cells/test_formula.py
@@ -105,4 +105,29 @@ def test_set_formula_with_defined_sub(sample_for_rename_and_formula):
 
     assert not len(foo)
     # assert len(sub1.Child1.Foo)         # Not Cleared
-    # assert sub1.Child1.Foo(1) == 3      # Not Changed
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+    # assert sub1.Child1.Foo(1) == 3      # Not Changed
+
+
+def test_set_base_formula_with_defined_sub():
+    """Setting the formula of a base cells not affecting its sub
+
+    https://github.com/fumitoh/modelx/issues/141
+
+    Base----foo
+       +----Sub1---foo(defined)
+       +----Sub2---foo(derived)
+    """
+    m = mx.new_model()
+    base = m.new_space('Base')
+    sub1 = m.new_space('Sub1', bases=base)
+    sub2 = m.new_space('Sub2', bases=base)
+
+    sub1.new_cells('foo')
+    base.new_cells('foo')
+    assert 'foo' in sub2
+
+    @mx.defcells(space=base)
+    def foo():
+        return "base"
+
+    assert sub2.foo() == "base"
\ No newline at end of file