diff --git a/pybamm/models/base_model.py b/pybamm/models/base_model.py
index 1589018b85..eed365960b 100644
--- a/pybamm/models/base_model.py
+++ b/pybamm/models/base_model.py
@@ -285,8 +285,6 @@ def timescale(self):
     @timescale.setter
     def timescale(self, value):
         """Set the timescale"""
-        if not isinstance(value, (numbers.Number, pybamm.Scalar)):
-            raise ValueError("model.timescale must be a scalar")
         self._timescale = value
 
     @property
diff --git a/pybamm/solvers/base_solver.py b/pybamm/solvers/base_solver.py
index 4cbbbf549b..2f770d231f 100644
--- a/pybamm/solvers/base_solver.py
+++ b/pybamm/solvers/base_solver.py
@@ -143,7 +143,10 @@ def set_up(self, model, inputs=None, t_eval=None, ics_only=False):
         inputs = inputs or {}
 
         # Set model timescale
-        model.timescale_eval = model.timescale.evaluate(inputs=inputs)
+        if not isinstance(model.timescale, pybamm.Scalar):
+            raise ValueError("model.timescale must be a scalar")
+
+        model.timescale_eval = model.timescale.evaluate()
         # Set model lengthscales
         model.length_scales_eval = {
             domain: scale.evaluate(inputs=inputs)
diff --git a/tests/unit/test_models/test_base_model.py b/tests/unit/test_models/test_base_model.py
index 69a8ca48cf..c56d2802f3 100644
--- a/tests/unit/test_models/test_base_model.py
+++ b/tests/unit/test_models/test_base_model.py
@@ -935,13 +935,6 @@ def test_set_variables_error(self):
         with self.assertRaisesRegex(ValueError, "not var"):
             model.variables = {"not var": var}
 
-    def test_timescale(self):
-        model = pybamm.BaseModel()
-        model.timescale = 2.5
-        self.assertEqual(model.timescale, 2.5)
-        with self.assertRaisesRegex(ValueError, "must be a scalar"):
-            model.timescale = pybamm.InputParameter("a")
-
 
 if __name__ == "__main__":
     print("Add -v for more debug output")
diff --git a/tests/unit/test_solvers/test_base_solver.py b/tests/unit/test_solvers/test_base_solver.py
index c35325e0ba..9d5bcd9bce 100644
--- a/tests/unit/test_solvers/test_base_solver.py
+++ b/tests/unit/test_solvers/test_base_solver.py
@@ -282,6 +282,18 @@ def test_convert_to_casadi_format(self):
         self.assertEqual(model.convert_to_format, "casadi")
         pybamm.set_logging_level("WARNING")
 
+    def test_timescale_input_fail(self):
+        # Make sure timescale can't depend on inputs
+        model = pybamm.BaseModel()
+        v = pybamm.Variable("v")
+        model.rhs = {v: -1}
+        model.initial_conditions = {v: 1}
+        a = pybamm.InputParameter("a")
+        model.timescale = a
+        solver = pybamm.BaseSolver()
+        with self.assertRaisesRegex(ValueError, "model.timescale must be a scalar"):
+            solver.set_up(model)
+
     def test_inputs_step(self):
         # Make sure interpolant inputs are dropped
         model = pybamm.BaseModel()