diff --git a/GPy/inference/latent_function_inference/var_dtc.py b/GPy/inference/latent_function_inference/var_dtc.py
index b56cf77c..ebc5aa88 100644
--- a/GPy/inference/latent_function_inference/var_dtc.py
+++ b/GPy/inference/latent_function_inference/var_dtc.py
@@ -239,7 +239,7 @@ class VarDTCMissingData(LatentFunctionInference):
             logger.info('preparing subarrays Y')
             Ys = [Y[v, :][:, ind] for v, ind in self._subarray_indices]
             logger.info('preparing traces Y')
-            traces = [(y**2).sum() for y in Ys]
+            traces = [np.einsum('ij,ij->', y,y) for y in Ys]
             return Ys, traces
         else:
             self._subarray_indices = [[slice(None),slice(None)]]