diff --git a/brainunit/_base.py b/brainunit/_base.py
index f1f6247..f64aace 100644
--- a/brainunit/_base.py
+++ b/brainunit/_base.py
@@ -37,8 +37,8 @@
   # helpers
   'DimensionMismatchError',
   'UnitMismatchError',
+  'is_dimensionless',
   'is_unitless',
-  'display_in_unit',
   'get_dim',
   'get_unit',
 
@@ -698,7 +698,6 @@ def has_same_unit(obj1, obj2) -> bool:
   return unit1 == unit2
 
 
-
 def fail_for_dimension_mismatch(
     obj1, obj2=None, error_message=None, **error_arrays
 ):
@@ -974,7 +973,7 @@ def array_with_unit(
   return Quantity(floatval, dim=get_or_create_dimension(dim._dims), dtype=dtype)
 
 
-def is_unitless(obj: Union['Quantity', 'Unit', jax.typing.ArrayLike]) -> bool:
+def is_dimensionless(obj: Union['Quantity', 'Unit', 'Dimension', jax.typing.ArrayLike]) -> bool:
   """
   Test if a value is dimensionless or not.
 
@@ -988,6 +987,26 @@ def is_unitless(obj: Union['Quantity', 'Unit', jax.typing.ArrayLike]) -> bool:
   dimensionless : `bool`
       ``True`` if `obj` is dimensionless.
   """
+  if isinstance(obj, Dimension):
+    return obj.is_dimensionless
+  return _to_quantity(obj).dim.is_dimensionless
+
+
+def is_unitless(obj: Union['Quantity', 'Unit', jax.typing.ArrayLike]) -> bool:
+  """
+  Test if a value is unitless or not.
+
+  Parameters
+  ----------
+  obj : `object`
+      The object to check.
+
+  Returns
+  -------
+  unitless : `bool`
+      ``True`` if `obj` is unitless.
+  """
+  assert not isinstance(obj, Dimension), f"Dimension objects are not unitless or not, but got {obj}"
 
   return _to_quantity(obj).is_unitless
 
diff --git a/brainunit/math/_fun_accept_unitless_test.py b/brainunit/math/_fun_accept_unitless_test.py
index f1f2848..bd12871 100644
--- a/brainunit/math/_fun_accept_unitless_test.py
+++ b/brainunit/math/_fun_accept_unitless_test.py
@@ -4,7 +4,8 @@
 
 import brainunit as bu
 import brainunit.math as bm
-from brainunit import meter, DimensionMismatchError, assert_quantity
+from brainunit import meter, DimensionMismatchError
+from brainunit._base import assert_quantity
 
 fun_accept_unitless_unary = [
   'exp', 'exp2', 'expm1', 'log', 'log10', 'log1p', 'log2',
diff --git a/brainunit/math/_fun_array_creation_test.py b/brainunit/math/_fun_array_creation_test.py
index 8d595b3..34894cd 100644
--- a/brainunit/math/_fun_array_creation_test.py
+++ b/brainunit/math/_fun_array_creation_test.py
@@ -4,7 +4,8 @@
 
 import brainunit as bu
 import brainunit.math as bm
-from brainunit import second, meter, DimensionMismatchError, assert_quantity
+from brainunit import second, meter, DimensionMismatchError
+from brainunit._base import assert_quantity
 
 fun_array_creation_given_shape = [
   'empty', 'ones', 'zeros',
diff --git a/brainunit/math/_fun_change_unit_test.py b/brainunit/math/_fun_change_unit_test.py
index 9dd58c4..29dc243 100644
--- a/brainunit/math/_fun_change_unit_test.py
+++ b/brainunit/math/_fun_change_unit_test.py
@@ -4,7 +4,8 @@
 
 import brainunit as bu
 import brainunit.math as bm
-from brainunit import meter, second, assert_quantity, volt, get_dim
+from brainunit import meter, second, volt, get_dim
+from brainunit._base import assert_quantity
 
 fun_change_unit_unary = [
   'reciprocal', 'var', 'nanvar', 'cbrt', 'square', 'sqrt',
diff --git a/brainunit/math/_fun_keep_unit_test.py b/brainunit/math/_fun_keep_unit_test.py
index 5e37c67..10f872f 100644
--- a/brainunit/math/_fun_keep_unit_test.py
+++ b/brainunit/math/_fun_keep_unit_test.py
@@ -4,7 +4,8 @@
 
 import brainunit as bu
 import brainunit.math as bm
-from brainunit import assert_quantity, second, meter, ms
+from brainunit import second, meter, ms
+from brainunit._base import assert_quantity
 
 fun_keep_unit_squence_inputs = [
   'row_stack', 'concatenate', 'stack', 'vstack', 'hstack', 'dstack', 'column_stack', 'block', 'append',
diff --git a/brainunit/math/_fun_remove_unit_test.py b/brainunit/math/_fun_remove_unit_test.py
index f791f14..76fecc0 100644
--- a/brainunit/math/_fun_remove_unit_test.py
+++ b/brainunit/math/_fun_remove_unit_test.py
@@ -7,7 +7,8 @@
 
 import brainunit as bu
 import brainunit.math as bm
-from brainunit import assert_quantity, DimensionMismatchError
+from brainunit import DimensionMismatchError
+from brainunit._base import assert_quantity
 
 fun_remove_unit_unary = [
   'signbit', 'sign',