diff --git a/thinc/tests/test_util.py b/thinc/tests/test_util.py
index b51f23a19..715d381d5 100644
--- a/thinc/tests/test_util.py
+++ b/thinc/tests/test_util.py
@@ -46,7 +46,9 @@ def test_array_module_cpu_gpu_helpers():
     assert not is_numpy_array((1, 2))
 
 
-@given(label_smoothing=strategies.floats(min_value=0.0, max_value=0.5))
+@given(
+    label_smoothing=strategies.floats(min_value=0.0, max_value=0.5, exclude_max=True)
+)
 def test_to_categorical(label_smoothing):
     # Test without n_classes
     one_hot = to_categorical(numpy.asarray([1, 2], dtype="i"))