diff --git a/GPy/kern/parts/rbf.py b/GPy/kern/parts/rbf.py
index e549a14a..027aa382 100644
--- a/GPy/kern/parts/rbf.py
+++ b/GPy/kern/parts/rbf.py
@@ -247,7 +247,6 @@ class RBF(Kernpart):
         target = np.zeros(self.input_dim)
         dvardLdK = self._K_dvar * dL_dK
         var_len3 = self.variance / np.power(self.lengthscale, 3)
-        var_len3 = param_to_array(var_len3)
         if X2 is None:
             # save computation for the symmetrical case
             dvardLdK = dvardLdK + dvardLdK.T