diff --git a/CI/CI.ml b/CI/CI.ml
index 0f425b2..0bd935f 100644
--- a/CI/CI.ml
+++ b/CI/CI.ml
@@ -490,7 +490,7 @@ let make ?(n_states=1) ?(algo=`Direct) det_space =
       in
       let matrix_prod psi = 
         let result = 
-          Matrix.parallel_mm ~transa:`T psi m_H
+          Matrix.parallel_mm ~transa:`T ~transb:`T psi m_H
           |> Matrix.transpose
         in
         Parallel.broadcast (lazy result)
diff --git a/Utils/Matrix.ml b/Utils/Matrix.ml
index 53f6c85..0dbfad4 100644
--- a/Utils/Matrix.ml
+++ b/Utils/Matrix.ml
@@ -201,7 +201,8 @@ let rec mm ?(transa=`N) ?(transb=`N) ?(threshold=epsilon) a b =
     | `N, `T -> dim2, dim2
   in
   if f a <> f' b then
-      invalid_arg "Inconsistent dimensions";
+      Printf.sprintf "%d %d : Inconsistent dimensions" (f a) (f' b)
+      |> invalid_arg;
 
   (* Dense x sparse *)
   let mmsp transa transb a b =
@@ -560,16 +561,21 @@ let parallel_mm ?(transa=`N) ?(transb=`N) ?(threshold=epsilon) a b =
     | `N -> dim2 a
     | `T -> dim1 a
   in
-  let n = n / (Parallel.size * 4) in
+  let n = n / (Parallel.size * 7) in
+  let b = 
+    match transb with
+    | `T -> transpose b
+    | `N -> b
+  in
   split_cols n b
   |> Stream.of_list 
   |> Farm.run ~ordered:true ~f:(fun b ->
             match a, b with
               | Computed _, Computed _ -> 
-                  mm ~transa ~transb ~threshold a b
+                  mm ~transa ~threshold a b
                   |> sparse_of_computed ~threshold
               | _ ->
-                  mm ~transa ~transb ~threshold a b
+                  mm ~transa ~threshold a b
             )
   |> Util.stream_to_list
   |> join_cols