diff --git a/smithplot/smithaxes.py b/smithplot/smithaxes.py
index 2ed8cbb..841bc36 100644
--- a/smithplot/smithaxes.py
+++ b/smithplot/smithaxes.py
@@ -728,7 +728,7 @@ def plot(self, *args, **kwargs):
                     pass
 
             # if (converted) arg is an ndarray of complex type, split it
-            if isinstance(arg, np.ndarray) and arg.dtype in [np.complex, np.complex128]:
+            if isinstance(arg, np.ndarray) and arg.dtype in [complex, np.complex128]:
                 new_args += z_to_xy(arg)
             else:
                 new_args += (arg,)