diff --git a/tupak/gw/prior.py b/tupak/gw/prior.py
index 892f64f6e0118feefd459afbec77ecdf67855bb1..7594c0eedcd10a77db802632de4586f23e329870 100644
--- a/tupak/gw/prior.py
+++ b/tupak/gw/prior.py
@@ -1,5 +1,12 @@
-import tupak.core.prior
+from __future__ import division
+import tupak
 import os
+import logging
+import numpy as np
+from scipy.interpolate import interp1d
+from scipy.integrate import cumtrapz
+from scipy.special import erf, erfinv
+import scipy.stats
 
 
 class UniformComovingVolume(tupak.core.prior.FromFile):