diff --git a/brainpy/_src/math/delayvars.py b/brainpy/_src/math/delayvars.py
index da0cc542..3ee2e82e 100644
--- a/brainpy/_src/math/delayvars.py
+++ b/brainpy/_src/math/delayvars.py
@@ -583,7 +583,8 @@ def reset(
       batch_axis: int = None
   ):
     if not isinstance(delay_target, (ndarray, jnp.ndarray)):
-      raise ValueError(f'Must be an instance of brainpy.math.ndarray or jax.numpy.ndarray. But we got {type(delay_target)}')
+      raise ValueError(f'Must be an instance of brainpy.math.ndarray or ' 
+                       f'jax.numpy.ndarray. But we got {type(delay_target)}')
 
     # delay_len
     # is_integer(delay_len, 'delay_len', allow_none=True, min_bound=0)