diff --git a/GPy/core/gp.py b/GPy/core/gp.py
index a7dac56e..1c9302bb 100644
--- a/GPy/core/gp.py
+++ b/GPy/core/gp.py
@@ -6,6 +6,7 @@ import pylab as pb
 import warnings
 from .. import kern
 from ..util.plot import gpplot, Tango, x_frame1D, x_frame2D
+from ..util.linalg import dtrtrs
 from model import Model
 from parameterization import ObservableArray
 from .. import likelihoods