diff --git a/src/compiler.ml b/src/compiler.ml
index 0eed3ede3..9434198cb 100644
--- a/src/compiler.ml
+++ b/src/compiler.ml
@@ -105,10 +105,12 @@ type table = {
   uuid : Util.UUID.t;
 } [@@deriving show]
 
-type pruned_table = {
-  c2s0 : string D.Constants.Map.t;
-  c2t0 : D.term D.Constants.Map.t;
-} [@@deriving show]
+type entry =
+| GlobalSymbol of D.constant * string
+| BoundVariable of D.constant * D.term
+[@@deriving show]
+
+type pruned_table = entry array [@@deriving show]
 
 let locked { locked } = locked
 let lock t = { t with locked = true }
@@ -116,16 +118,24 @@ let uuid { uuid } = uuid
 let equal t1 t2 =
   locked t1 && locked t2 && uuid t1 = uuid t2
 
-let size t = D.Constants.Map.cardinal t.c2t0
+let size t = Array.length t
 
-let symbols { c2s0 } =
-  List.map (fun (c,s) -> s ^ ":" ^ string_of_int c) (D.Constants.Map.bindings c2s0)
+let symbols table =
+  let map = function
+  | GlobalSymbol (c, s) -> Some (s ^ ":" ^ string_of_int c)
+  | BoundVariable _ -> None
+  in
+  List.rev @@ List.filter_map map @@ Array.to_list table
 
 let prune t ~alive =
-  {
-    c2s0 = D.Constants.Map.filter (fun k _ -> D.Constants.Set.mem k alive) t.c2s;
-    c2t0 = D.Constants.Map.filter (fun k _ -> D.Constants.Set.mem k alive) t.c2t;
-  }
+  let c2s = t.c2s in
+  let c2t0 = D.Constants.Map.filter (fun k _ -> D.Constants.Set.mem k alive) t.c2t in
+  let map k t =
+    if k < 0 then GlobalSymbol (k, D.Constants.Map.find k c2s)
+    else BoundVariable (k, t)
+  in
+  let c2t0 = D.Constants.Map.mapi map c2t0 in
+  Array.of_list @@ List.rev_map snd @@ D.Constants.Map.bindings c2t0
 
 let table = D.State.declare
   ~descriptor:D.elpi_state_descriptor
@@ -247,10 +257,10 @@ let build_shift ?(lock_base=false) ~flags:{ print_units } ~base symbols =
     (* We try hard to respect the same order if possible, since some tests
        (grundlagen) depend on this order (for performance, the constant-timestamp
        heuristic in unfolding) *)
-    List.fold_left (fun (base,shift as acc) (v, t) ->
-      if v < 0 then
-        let name = Map.find v symbols.c2s0 in
-        try
+    Array.fold_left (fun (base,shift as acc) e ->
+      match e with
+      | GlobalSymbol (v, name) ->
+        begin try
           let c, _ = F.Map.find (F.from_string name)  base.ast2ct in
           if c == v then acc
           else begin
@@ -262,13 +272,14 @@ let build_shift ?(lock_base=false) ~flags:{ print_units } ~base symbols =
         | Not_found ->
           let base, (c,_) = allocate_global_symbol_aux (Ast.Func.from_string name) base in
           base, Map.add v c shift
-      else
+        end
+      | BoundVariable (v, t) ->
         if Map.mem v base.c2t then acc
         else
           let base = { base with c2t = Map.add v t base.c2t } in
           base, shift
       )
-     (base,Map.empty)  (List.rev (Map.bindings symbols.c2t0)))
+     (base, Map.empty) symbols)
 
 let build_shift ?lock_base ~flags ~base symbols =
   try Stdlib.Result.Ok (build_shift ?lock_base ~flags ~base symbols)
@@ -533,9 +544,6 @@ type program = {
   clauses : (preterm,Ast.Structured.attribute) Ast.Clause.t list;
   chr : (constant list * prechr_rule list) list;
   local_names : int;
-  symbols : C.Set.t;
-
-  toplevel_macros : macro_declaration;
 }
 [@@deriving show]
 
@@ -579,7 +587,7 @@ type compilation_unit = {
 
 type builtins = string * Data.BuiltInPredicate.declaration list
 
-type header = State.t * compilation_unit
+type header = State.t * compilation_unit * macro_declaration
 type program = State.t * Assembled.program
 
 
@@ -1497,7 +1505,7 @@ module Flatten : sig
 
   (* Eliminating the structure (name spaces) *)
 
-  val run : State.t -> Structured.program -> Flat.program
+  val run : State.t -> Structured.program -> C.Set.t * macro_declaration * Flat.program
 
   val relocate : State.t -> D.constant D.Constants.Map.t -> Flat.program  -> Flat.program
   val relocate_term : State.t -> D.constant D.Constants.Map.t -> term -> term
@@ -1696,14 +1704,12 @@ let subst_amap state f { nargs; c2i; i2n; n2t; n2i } =
     let modes = apply_subst_modes ~live_symbols empty_subst modes in
     let types, type_abbrevs, modes, clauses, chr =
       compile_body live_symbols state local_names types type_abbrevs modes [] [] empty_subst body in
-    { Flat.types;
+    !live_symbols, toplevel_macros, { Flat.types;
       type_abbrevs;
       modes;
       clauses;
       chr = List.rev chr;
       local_names;
-      toplevel_macros;
-      symbols = !live_symbols
     }
     let relocate_term state s t =
       let ksub = apply_subst_constant ([],s) in
@@ -1716,8 +1722,6 @@ let subst_amap state f { nargs; c2i; i2n; n2t; n2i } =
       clauses;
       chr;
       local_names;
-      toplevel_macros;
-      symbols;
     } =
       let f = [], f in
     {
@@ -1727,8 +1731,6 @@ let subst_amap state f { nargs; c2i; i2n; n2t; n2i } =
       clauses = apply_subst_clauses state f clauses;
       chr = smart_map (apply_subst_chr state f) chr;
       local_names;
-      toplevel_macros;
-      symbols;
     }
 
 
@@ -2073,7 +2075,7 @@ let assemble flags state code  (ul : compilation_unit list) =
 
   let state, clauses_rev, types, type_abbrevs, modes, chr_rev =
     List.fold_left (fun (state, cl1, t1, ta1, m1, c1) ({ symbol_table; code }  as _u) ->
-      let state, { Flat.clauses = cl2; types = t2; type_abbrevs = ta2; modes = m2; chr = c2; toplevel_macros = _ } =
+      let state, { Flat.clauses = cl2; types = t2; type_abbrevs = ta2; modes = m2; chr = c2; } =
         let state, shift = Stdlib.Result.get_ok @@ Symbols.build_shift ~flags ~base:state symbol_table in
         let code =
           if C.Map.is_empty shift then code
@@ -2146,7 +2148,7 @@ let unit_or_header_of_ast { print_passes } s ?(toplevel_macros=F.Map.empty) p =
     Format.eprintf "== Structured ================@\n@[<v 0>%a@]@\n"
       (w_symbol_table s Structured.pp_program) p;
 
-  let p = Flatten.run s p in
+  let alive, toplevel_macros, p = Flatten.run s p in
 
   if print_passes then
     Format.eprintf "== Flat ================@\n@[<v 0>%a@]@\n"
@@ -2155,8 +2157,8 @@ let unit_or_header_of_ast { print_passes } s ?(toplevel_macros=F.Map.empty) p =
   s, {
     version = "%%VERSION_NUM%%";
     code = p;
-    symbol_table = Symbols.prune (State.get Symbols.table s) ~alive:p.Flat.symbols
-  }
+    symbol_table = Symbols.prune (State.get Symbols.table s) ~alive
+  }, toplevel_macros
 ;;
 
 let print_unit { print_units } x =
@@ -2199,17 +2201,16 @@ let header_of_ast ~flags ~parser:p state_descriptor quotation_descriptor hoas_de
       | Data.BuiltInPredicate.MLDataC _ -> state
       | Data.BuiltInPredicate.LPCode _ -> state
       | Data.BuiltInPredicate.LPDoc _ -> state) state decls) state builtins in
-  let state, u = unit_or_header_of_ast flags state ast in
+  let state, u, toplevel_macros = unit_or_header_of_ast flags state ast in
   print_unit flags u;
-  state, u
+  state, u, toplevel_macros
 
-let unit_of_ast ~flags ~header:(s, (header : compilation_unit)) p : compilation_unit =
-  let toplevel_macros = header.code.Flat.toplevel_macros in
-  let _, u = unit_or_header_of_ast flags s ~toplevel_macros p in
+let unit_of_ast ~flags ~header:(s, (header : compilation_unit), toplevel_macros) p : compilation_unit =
+  let _, u, _ = unit_or_header_of_ast flags s ~toplevel_macros p in
   print_unit flags u;
   u
 
-let assemble_units ~flags ~header:(s,h) units : program =
+let assemble_units ~flags ~header:(s,h,toplevel_macros) units : program =
 
   let nunits_with_locals =
     (h :: units) |> List.filter (fun {code = { Flat.local_names = x }} -> x > 0) |> List.length in
@@ -2217,7 +2218,7 @@ let assemble_units ~flags ~header:(s,h) units : program =
   if nunits_with_locals > 0 then
     error "Only 1 compilation unit is supported when local directives are used";
 
-  let init = { Assembled.empty with toplevel_macros = h.code.toplevel_macros; local_names = h.code.local_names } in
+  let init = { Assembled.empty with toplevel_macros; local_names = h.code.local_names } in
 
   let s, p = Assemble.assemble flags s init (h :: units) in