diff --git a/brainpy/_src/math/compat_numpy.py b/brainpy/_src/math/compat_numpy.py
index 0eb39145..ddbaafd3 100644
--- a/brainpy/_src/math/compat_numpy.py
+++ b/brainpy/_src/math/compat_numpy.py
@@ -10,7 +10,6 @@
 from .interoperability import *
 from .ndarray import Array
 
-
 __all__ = [
   'full', 'full_like', 'eye', 'identity', 'diag', 'tri', 'tril', 'triu',
   'empty', 'empty_like', 'ones', 'ones_like', 'zeros', 'zeros_like',
@@ -204,11 +203,12 @@ def ascontiguousarray(a, dtype=None, order=None):
   return asarray(a, dtype=dtype, order=order)
 
 
-def asfarray(a, dtype=np.float_):
+def asfarray(a, dtype=None):
   if not np.issubdtype(dtype, np.inexact):
-    dtype = np.float_
+    dtype = np.float64
   return asarray(a, dtype=dtype)
 
+
 def in1d(ar1, ar2, assume_unique: bool = False, invert: bool = False) -> Array:
   del assume_unique
   ar1_flat = ravel(ar1)
@@ -227,6 +227,7 @@ def in1d(ar1, ar2, assume_unique: bool = False, invert: bool = False) -> Array:
   else:
     return asarray((ar1_flat[:, None] == ar2_flat[None, :]).any(-1))
 
+
 # Others
 # ------
 meshgrid = _compatible_with_brainpy_array(jnp.meshgrid)
@@ -454,7 +455,6 @@ def msort(a):
 sometrue = any
 
 
-
 def shape(a):
   """
   Return the shape of an array.
@@ -648,7 +648,6 @@ def size(a, axis=None):
 finfo = jnp.finfo
 iinfo = jnp.iinfo
 
-
 can_cast = _compatible_with_brainpy_array(jnp.can_cast)
 choose = _compatible_with_brainpy_array(jnp.choose)
 copy = _compatible_with_brainpy_array(jnp.copy)