diff --git a/src/orion/core/worker/transformer.py b/src/orion/core/worker/transformer.py
index 75fa7fd48..991bc6188 100644
--- a/src/orion/core/worker/transformer.py
+++ b/src/orion/core/worker/transformer.py
@@ -183,6 +183,13 @@ def reverse(self, transformed_point):
         transformed_point = self.apply.reverse(transformed_point)
         return self.composition.reverse(transformed_point)
 
+    def interval(self, alpha=1.0):
+        """Return interval of composed transformation."""
+        if hasattr(self.apply, 'interval'):
+            return self.apply.interval(alpha)
+
+        return None
+
     def infer_target_shape(self, shape):
         """Return the shape of the dimension after transformation."""
         shape = self.composition.infer_target_shape(shape)
@@ -370,6 +377,14 @@ def reverse(self, transformed_point):
         assert point_.shape[-1] == self.num_cats
         return point_.argmax(axis=-1)
 
+    # pylint:disable=unused-argument
+    def interval(self, alpha=1.0):
+        """Return the interval for the one-hot encoding in proper shape."""
+        low = numpy.zeros(self.num_cats)
+        high = numpy.ones(self.num_cats)
+
+        return low, high
+
     def infer_target_shape(self, shape):
         """Infer that transformed points will have one more tensor dimension,
         if the number of supported integers to transform is larger than 2.
@@ -411,7 +426,11 @@ def sample(self, n_samples=1, seed=None):
 
     def interval(self, alpha=1.0):
         """Map the interval bounds to the transformed ones."""
-        if self.original_dimension.prior_name == 'choices':
+        if hasattr(self.transformer, 'interval'):
+            interval = self.transformer.interval()
+            if interval:
+                return interval
+        elif self.original_dimension.prior_name == 'choices':
             return self.original_dimension.categories
 
         low, high = self.original_dimension.interval(alpha)
diff --git a/tests/unittests/core/test_transformer.py b/tests/unittests/core/test_transformer.py
index 0bb2b6955..c00d1e86f 100644
--- a/tests/unittests/core/test_transformer.py
+++ b/tests/unittests/core/test_transformer.py
@@ -430,6 +430,13 @@ def test_reverse(self):
         assert numpy.all(t.reverse([[0.5, 0], [1.0, 55]]) == numpy.array([[0, 0], [0, 0]],
                                                                          dtype=int))
 
+    def test_interval(self):
+        """Test that the onehot interval has the proper dimensions"""
+        t = OneHotEncode(3)
+        low, high = t.interval()
+        assert (low == numpy.zeros(3)).all()
+        assert (high == numpy.ones(3)).all()
+
     def test_infer_target_shape(self):
         """Check if it infers the shape of a transformed `Dimension`."""
         t = OneHotEncode(3)
@@ -531,7 +538,9 @@ def test_interval(self, tdim):
 
     def test_interval_from_categorical(self, tdim2):
         """Check how we should treat interval when original dimension is categorical."""
-        assert tdim2.interval() == ('asdfa', '2', '3', '4')
+        low, high = tdim2.interval()
+        assert (low == numpy.zeros(4)).all()
+        assert (high == numpy.ones(4)).all()
 
     def test_contains(self, tdim):
         """Check method `__contains__`."""