diff --git a/CHANGELOG.md b/CHANGELOG.md
index 162a0d0..a563ff2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,12 @@
 
 ### Deprecation
 
+### v0.3.3
+
+### Maintenance and fixes
+
+- Fixed a bug in `CategoricalBox`. Now it considers the order of the categories if `data` is ordered and `levels` is `None` (#73)
+
 ### v0.3.2
 
 ### Maintenance and fixes
diff --git a/formulae/categorical.py b/formulae/categorical.py
index 818030b..cbcd0fa 100644
--- a/formulae/categorical.py
+++ b/formulae/categorical.py
@@ -76,6 +76,9 @@ class CategoricalBox:
     """
 
     def __init__(self, data, contrast, levels):
+        # If 'data' is ordered and no explicit levels have been passed, use order in 'data'.
+        if hasattr(data.dtype, "ordered") and data.dtype.ordered and levels is None:
+            levels = data.dtype.categories.tolist()
         self.data = data
         self.contrast = contrast
         self.levels = levels
@@ -198,7 +201,7 @@ def __init__(self, omit=None):
     def _omit_index(self, levels):
         """Returns a number between 0 and len(levels) - 1"""
         if self.omit is None:
-            # By default, omit the lats level.
+            # By default, omit the last level.
             return len(levels) - 1
         else:
             return levels.index(self.omit)
diff --git a/formulae/tests/test_design_matrices.py b/formulae/tests/test_design_matrices.py
index fdc19c0..1912921 100644
--- a/formulae/tests/test_design_matrices.py
+++ b/formulae/tests/test_design_matrices.py
@@ -1133,7 +1133,18 @@ def test_extra_namespace(data):
     assert df["myfunc(x3)"].equals(np.log(df["x3"]))
 
 
-def test_categorical_series():
-    data = pd.DataFrame({"x": list("abc") * 10})
-    data["x"] = pd.Categorical(data["x"], list("abc"), ordered=True)
+def test_categorical_ordered_series():
+    # Test it works
+    data = pd.DataFrame({"x": list("abcd") * 10})
+    data["x"] = pd.Categorical(data["x"], list("bcda"), ordered=True)
     design_matrices("S(x)", data)
+
+    # Test it works and it respects original order
+    levels = design_matrices("x", data).common.terms["x"].levels
+    assert levels == list("cda")
+
+    levels = design_matrices("T(x)", data).common.terms["T(x)"].levels
+    assert levels == list("cda")
+
+    levels = design_matrices("S(x)", data).common.terms["S(x)"].levels
+    assert levels == list("bcd")
diff --git a/formulae/version.py b/formulae/version.py
index f9aa3e1..e19434e 100644
--- a/formulae/version.py
+++ b/formulae/version.py
@@ -1 +1 @@
-__version__ = "0.3.2"
+__version__ = "0.3.3"