diff --git a/Basis/TwoElectronIntegralsNonSeparable.ml b/Basis/TwoElectronIntegralsNonSeparable.ml
index 39b12b8..5d73675 100644
--- a/Basis/TwoElectronIntegralsNonSeparable.ml
+++ b/Basis/TwoElectronIntegralsNonSeparable.ml
@@ -235,7 +235,7 @@ module Make(Zero_m : Zero_mType) = struct
     let t0 = Unix.gettimeofday () in
     let ishell = ref max_int in
 
-    let input_stream = Stream.of_list (List.rev shell_pairs) in
+    let input_stream = Stream.of_list shell_pairs in
 
     let f shell_p =
       let () = 
@@ -248,31 +248,33 @@ module Make(Zero_m : Zero_mType) = struct
       in
 
       let result = ref [] in
-      try
-        List.iter (fun shell_q ->
-            let () = 
-              if  Cs.index (Csp.shell_a shell_q) >
-                  Cs.index (Csp.shell_a shell_p) then
-                raise Exit
-            in
-            let sq = Csp.shell_pairs shell_q in
-            let cspc = 
-              if Array.length sp < Array.length sq then
-                Cspc.make ~cutoff shell_p shell_q
-              else
-                Cspc.make ~cutoff shell_q shell_p
-            in
-
-            match cspc with
-            | Some cspc ->
-              let cls =
-                class_of_contracted_shell_pair_couple cspc
+      let () =
+        try
+          List.iter (fun shell_q ->
+              let () = 
+                if  Cs.index (Csp.shell_a shell_q) >
+                    Cs.index (Csp.shell_a shell_p) then
+                  raise Exit
               in
-              result := (store_class_parallel ~cutoff cspc cls) :: !result;
-            | None -> ()
-          ) shell_pairs;
-        raise Exit
-      with Exit -> List.concat !result |> Array.of_list
+              let sq = Csp.shell_pairs shell_q in
+              let cspc = 
+                if Array.length sp < Array.length sq then
+                  Cspc.make ~cutoff shell_p shell_q
+                else
+                  Cspc.make ~cutoff shell_q shell_p
+              in
+
+              match cspc with
+              | Some cspc ->
+                let cls =
+                  class_of_contracted_shell_pair_couple cspc
+                in
+                result := (store_class_parallel ~cutoff cspc cls) :: !result;
+              | None -> ()
+            ) shell_pairs;
+        with Exit -> ()
+      in
+      List.concat !result |> Array.of_list
     in
 
     let eri_array =