diff --git a/src/SM.ml b/src/SM.ml
index 8397571b2..f42ee33b8 100644
--- a/src/SM.ml
+++ b/src/SM.ml
@@ -14,6 +14,8 @@ type scope = {
 }
 [@@deriving gt ~options:{ show }]
 
+let label s = "L" ^ s
+let scope_label i s = label s ^ "_" ^ string_of_int i
 let show_scope = show scope
 
 (* The type for the stack machine instructions *)
@@ -265,13 +267,13 @@ module ByteCode = struct
           add_fixup s;
           add_ints [ 0 ]
       (* 0x70                 *)
-      | CALL ("Lread", _, _) -> add_bytes [ (7 * 16) + 0 ]
+      | CALL (f, _, _) when f = label "read" -> add_bytes [ (7 * 16) + 0 ]
       (* 0x71                 *)
-      | CALL ("Lwrite", _, _) -> add_bytes [ (7 * 16) + 1 ]
+      | CALL (f, _, _) when f = label "write" -> add_bytes [ (7 * 16) + 1 ]
       (* 0x72                 *)
-      | CALL ("Llength", _, _) -> add_bytes [ (7 * 16) + 2 ]
+      | CALL (f, _, _) when f = label "length" -> add_bytes [ (7 * 16) + 2 ]
       (* 0x73                 *)
-      | CALL ("Lstring", _, _) -> add_bytes [ (7 * 16) + 3 ]
+      | CALL (f, _, _) when f = label "string" -> add_bytes [ (7 * 16) + 3 ]
       (* 0x74                 *)
       | CALL (".array", n, _) ->
           add_bytes [ (7 * 16) + 4 ];
@@ -534,9 +536,10 @@ let[@ocaml.warning "-8-20"] rec eval env
           eval env
             (cstack, stack', glob, loc, i, o)
             (if
-             (c = "z" && Value.to_int x = 0) || (c = "nz" && Value.to_int x <> 0)
-            then env#labeled l
-            else prg')
+               (c = "z" && Value.to_int x = 0)
+               || (c = "nz" && Value.to_int x <> 0)
+             then env#labeled l
+             else prg')
       | CLOSURE (name, dgs) ->
           let closure =
             Array.of_list
@@ -802,8 +805,6 @@ let run p i =
    Takes a program in the source language and returns an equivalent program for the
    stack machine
 *)
-let label s = "L" ^ s
-let scope_label i s = label s ^ "_" ^ string_of_int i
 
 let check_name_and_add names name mut =
   if List.exists (fun (n, _) -> n = name) names then
diff --git a/src/X86.ml b/src/X86.ml
index bc3db60f2..1f893d905 100644
--- a/src/X86.ml
+++ b/src/X86.ml
@@ -1,5 +1,6 @@
 open GT
 open Language
+open SM
 
 (* X86 codegeneration interface *)
 
@@ -384,23 +385,31 @@ let compile_binop env op =
 
 let safepoint_functions =
   [
-    "Ls__Infix_58";
-    "Lsubstring";
-    "Lclone";
+    label "s__Infix_58";
+    label "substring";
+    label "clone";
     "Bstring";
-    "Lstringcat";
-    "Lstring";
+    label "stringcat";
+    label "string";
     "Bclosure";
     "Barray";
     "Bsexp";
-    "Li__Infix_4343"
-    (* "LmakeArray"; not required as do not have ptr arguments *)
-    (* "LmakeString"; not required as do not have ptr arguments *)
-    (* "LgetEnv", not required as do not have ptr arguments *)
+    label "i__Infix_4343"
+    (* "makeArray"; not required as do not have ptr arguments *)
+    (* "makeString"; not required as do not have ptr arguments *)
+    (* "getEnv", not required as do not have ptr arguments *)
     (* "set_args", not required as do not have ptr arguments *);
     (* Lsprintf, or Bsprintf is an extra dirty hack that works? *)
   ]
 
+let vararg_functions =
+  [
+    (label "printf", 1);
+    (label "fprintf", 2);
+    (label "sprintf", 1);
+    (label "failure", 1);
+  ]
+
 let compile_call env ?fname nargs tail =
   let fname =
     Option.map
@@ -485,9 +494,10 @@ let compile_call env ?fname nargs tail =
     in
     let add_printf_count =
       match fname with
-      | Some "Lprintf" | Some "Lsprintf" | Some "Lfailure" ->
-          [ Mov (L (nargs - 1), r11) ]
-      | Some "Lfprintf" -> [ Mov (L (nargs - 2), r11) ]
+      | Some fname -> (
+          match List.assoc_opt fname vararg_functions with
+          | Some n -> [ Mov (L (nargs - n), r11) ]
+          | None -> [])
       | _ -> []
     in
     let stack_slots, env, setup_args_code = setup_arguments env nargs in
@@ -714,10 +724,10 @@ let compile cmd env imports code =
                          CJmp ("z", "_continue");
                          Ret;
                          Label "_ERROR";
-                         Call "Lbinoperror";
+                         Call (label "binoperror");
                          Ret;
                          Label "_ERROR2";
-                         Call "Lbinoperror2";
+                         Call (label "binoperror2");
                          Ret;
                          Label "_continue";
                          Mov (L 1, M "_init");
@@ -1172,7 +1182,7 @@ class env prg =
 
     (* gets a number of stack positions allocated *)
     method allocated = stack_slots
-    method allocated_size = Printf.sprintf "LS%s_SIZE" fname
+    method allocated_size = label (Printf.sprintf "S%s_SIZE" fname)
 
     (* enters a function *)
     method enter f nargs nlocals has_closure =
@@ -1185,10 +1195,10 @@ class env prg =
        ; first_line = true>}
 
     (* returns a label for the epilogue *)
-    method epilogue = Printf.sprintf "L%s_epilogue" fname
+    method epilogue = label (Printf.sprintf "%s_epilogue" fname)
 
     (* returns a name for local size meta-symbol *)
-    method lsize = Printf.sprintf "L%s_SIZE" fname
+    method lsize = label (Printf.sprintf "%s_SIZE" fname)
 
     (* returns a list of live registers *)
     method live_registers =