diff --git a/brainpy/__init__.py b/brainpy/__init__.py
index c52358720..c8f834c6d 100644
--- a/brainpy/__init__.py
+++ b/brainpy/__init__.py
@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-__version__ = "2.4.6.post4"
+__version__ = "2.4.6.post5"
 
 # fundamental supporting modules
 from brainpy import errors, check, tools
diff --git a/brainpy/_src/math/ndarray.py b/brainpy/_src/math/ndarray.py
index 61746c038..81ccba932 100644
--- a/brainpy/_src/math/ndarray.py
+++ b/brainpy/_src/math/ndarray.py
@@ -108,6 +108,15 @@ def sharding(self):
   def addressable_shards(self):
     return self._value.addressable_shards
 
+  def __check_shape_dtype(self, other_value, self_value):
+    if other_value.shape != self_value.shape:
+      raise MathError(f"The shape of the original data is {self_value.shape}, "
+                      f"while we got {other_value.shape}.")
+    if other_value.dtype != self_value.dtype:
+      raise MathError(f"The dtype of the original data is {self_value.dtype}, "
+                      f"while we got {other_value.dtype}.")
+
+
   @property
   def value(self):
     # return the value
@@ -126,12 +135,8 @@ def value(self, value):
     else:
       value = jnp.asarray(value)
     # check
-    if value.shape != self_value.shape:
-      raise MathError(f"The shape of the original data is {self_value.shape}, "
-                      f"while we got {value.shape}.")
-    if value.dtype != self_value.dtype:
-      raise MathError(f"The dtype of the original data is {self_value.dtype}, "
-                      f"while we got {value.dtype}.")
+    self.__check_shape_dtype(value, self_value)
+    # assign
     self._value = value
 
   def update(self, value):
@@ -1569,12 +1574,8 @@ def value(self, value):
     else:
       value = jnp.asarray(value)
     # check
-    if value.shape != self_value.shape:
-      raise MathError(f"The shape of the original data is {self_value.shape}, "
-                      f"while we got {value.shape}.")
-    if value.dtype != self_value.dtype:
-      raise MathError(f"The dtype of the original data is {self_value.dtype}, "
-                      f"while we got {value.dtype}.")
+    self.__check_shape_dtype(value, self_value)
+    # assign
     self._value = value
 
 
diff --git a/brainpy/_src/math/object_transform/variables.py b/brainpy/_src/math/object_transform/variables.py
index 5014da0bf..35eea1774 100644
--- a/brainpy/_src/math/object_transform/variables.py
+++ b/brainpy/_src/math/object_transform/variables.py
@@ -240,14 +240,6 @@ def current_transform_number():
   return len(transform_stack)
 
 
-def _stack_add_read(var: 'Variable'):
-  pass
-
-
-def _stack_add_write(var: 'Variable'):
-  pass
-
-
 @register_pytree_node_class
 class Variable(Array):
   """The pointer to specify the dynamical variable.