diff --git a/brainunit/math/_compat_numpy_array_creation.py b/brainunit/math/_compat_numpy_array_creation.py
index 61ce599..d904d80 100644
--- a/brainunit/math/_compat_numpy_array_creation.py
+++ b/brainunit/math/_compat_numpy_array_creation.py
@@ -475,9 +475,10 @@ def asarray(
   Returns:
     Union[jax.Array, Quantity]: Quantity if `unit` is provided, else an array.
   """
+  if unit is not None:
+    assert isinstance(unit, Unit), f'unit must be an instance of Unit, got {type(unit)}'
   if isinstance(a, Quantity):
     if unit is not None:
-      assert isinstance(unit, Unit)
       fail_for_dimension_mismatch(a, unit, error_message="a and unit have to have the same units.")
     return Quantity(jnp.asarray(a.value, dtype=dtype, order=order), dim=a.dim)
   elif isinstance(a, (jax.Array, np.ndarray)):
@@ -494,8 +495,8 @@ def asarray(
       if any(x.dim != leaves[0].dim for x in leaves):
         raise ValueError('Units do not match for asarray operation.')
       values = jax.tree.unflatten(tree, [x.value for x in a])
-
-      fail_for_dimension_mismatch(a[0], unit, error_message="a and unit have to have the same units.")
+      if unit is not None:
+        fail_for_dimension_mismatch(a[0], unit, error_message="a and unit have to have the same units.")
       unit = a[0].dim
       # Convert the values to a jnp.ndarray and create a Quantity object
       return Quantity(jnp.asarray(values, dtype=dtype, order=order), dim=unit)
@@ -503,7 +504,6 @@ def asarray(
       values = jax.tree.unflatten(tree, leaves)
       val = jnp.asarray(values, dtype=dtype, order=order)
       if unit is not None:
-        assert isinstance(unit, Unit)
         return val * unit
       else:
         return val
diff --git a/brainunit/math/_compat_numpy_test.py b/brainunit/math/_compat_numpy_test.py
index 489e140..3c74dfb 100644
--- a/brainunit/math/_compat_numpy_test.py
+++ b/brainunit/math/_compat_numpy_test.py
@@ -162,6 +162,10 @@ def test_asarray(self):
     result_q = bu.math.asarray([1, 2, 3], unit=bu.second)
     assert_quantity(result_q, jnp.asarray([1, 2, 3]), bu.second)
 
+    a = bu.math.asarray([1 * bu.second, 2 * bu.second, 3 * bu.second], unit=bu.second)
+    b = bu.math.asarray([1 * bu.second, 2 * bu.second, 3 * bu.second])
+    assert bu.math.allclose(a, b)
+
   def test_arange(self):
     result = bu.math.arange(5)
     self.assertEqual(result.shape, (5,))