diff --git a/compiler/obc/java/java_main.ml b/compiler/obc/java/java_main.ml
index 7c836db..eb6fa19 100644
--- a/compiler/obc/java/java_main.ml
+++ b/compiler/obc/java/java_main.ml
@@ -1,5 +1,6 @@
 open Misc
 open Names
+open Modules
 open Signature
 open Java
 open Java_printer
@@ -22,6 +23,13 @@ let program p =
   (* Create a runnable main simulation *)
   if !Compiler_options.simulation
   then (
+    let q_main =
+      try !Compiler_options.simulation_node |> qualify_value
+      with Not_found ->
+        Format.eprintf "Unable to find main node: %s@." !Compiler_options.simulation_node;
+        raise Errors.Error
+    in
+    let ty_main = (find_value q_main).node_outputs |> types_of_arg_list |> Types.prod in
     let class_name = Obc2java.fresh_classe (!Compiler_options.simulation_node ^ "_sim") in
     Idents.enter_node class_name;
     let field_step_dnb, id_step_dnb =
@@ -34,9 +42,6 @@ let program p =
         mk_var (Tarray (Tclass (Names.pervasives_qn "String"), (Sint 0))) "args" in
       let body =
         let vd_main, e_main, q_main, ty_main =
-          let q_main = !Compiler_options.simulation_node |> Modules.qualify_value in (*qual*)
-          let ty_main =
-            (Modules.find_value q_main).node_outputs |> types_of_arg_list |> Types.prod in
           let q_main = Obc2java.qualname_to_package_classe q_main in (*java qual*)
           let id = Idents.gen_var "java_main" "main" in
           mk_var_dec id (Tclass q_main), Evar id, q_main, ty_main