diff --git a/CI/F12CI.ml b/CI/F12CI.ml
index 69384ee..f76f8d2 100644
--- a/CI/F12CI.ml
+++ b/CI/F12CI.ml
@@ -169,7 +169,11 @@ let dressing_vector ~frozen_core aux_basis f12_amplitudes ci =
         )
     in
     let result = 
-      let m_H_aux, m_F_aux = make_h_and_f [(Stream.next out_dets_stream)] in
+      let x = 
+        try [ Stream.next out_dets_stream ]
+        with Stream.Failure -> failwith "Auxiliary basis set does not produce any excited determinant"
+      in
+      let m_H_aux, m_F_aux = make_h_and_f x in
       let m_HF =
         gemm m_H_aux m_F_aux ~transb:`T 
       in
@@ -193,7 +197,7 @@ let dressing_vector ~frozen_core aux_basis f12_amplitudes ci =
     Parallel.broadcast (lazy result)
   in
 
-  Printf.printf "Done\n%!";
+  if Parallel.master then Printf.printf "Done\n%!";
   Matrix.dense_of_mat m_HF