diff --git a/GPy/core/sparse_gp_mpi.py b/GPy/core/sparse_gp_mpi.py
index d9c29a2f..d747ac83 100644
--- a/GPy/core/sparse_gp_mpi.py
+++ b/GPy/core/sparse_gp_mpi.py
@@ -108,6 +108,7 @@ class SparseGP_MPI(SparseGP):
                             raise
                         self._fail_count += 1
                 elif flag==-1:
+                    ret = None
                     break
                 else:
                     self._IN_OPTIMIZATION_ = False