diff --git a/ax/core/parameter.py b/ax/core/parameter.py
index 1e73f1720f0..fa4dc2a0e33 100644
--- a/ax/core/parameter.py
+++ b/ax/core/parameter.py
@@ -40,7 +40,7 @@
 # TODO: Do a more comprehensive audit of how floating point precision issues
 # may creep up and implement a more principled fix
 EPS = 1.5e-7
-MAX_VALUES_CHOICE_PARAM = 1000
+MAX_VALUES_CHOICE_PARAM = 1001
 FIXED_CHOICE_PARAM_ERROR = (
     "ChoiceParameters require multiple feasible values. "
     "Please use FixedParameter instead when setting a single possible value."
diff --git a/ax/core/tests/test_parameter.py b/ax/core/tests/test_parameter.py
index dc40742aa8f..a86ab05a7aa 100644
--- a/ax/core/tests/test_parameter.py
+++ b/ax/core/tests/test_parameter.py
@@ -490,17 +490,17 @@ def test_MaxValuesValidation(self) -> None:
         ChoiceParameter(
             name="x",
             parameter_type=ParameterType.INT,
-            values=list(range(999)),
+            values=list(range(1000)),
         )
         with self.assertRaisesRegex(
             UserInputError,
-            "`ChoiceParameter` with more than 1000 values is not supported! Use a "
+            "`ChoiceParameter` with more than 1001 values is not supported! Use a "
             "`RangeParameter` instead.",
         ):
             ChoiceParameter(
                 name="x",
                 parameter_type=ParameterType.INT,
-                values=list(range(1001)),
+                values=list(range(1002)),
             )
         # With bypass_cardinality_check=True, this should not raise an error.
         p = ChoiceParameter(