diff --git a/byterun/include/utils.h b/byterun/include/utils.h
index bb951075d..bb9eb6cb1 100644
--- a/byterun/include/utils.h
+++ b/byterun/include/utils.h
@@ -9,12 +9,13 @@
 
 /* The unpacked representation of bytecode file */
 typedef struct {
-  char *string_ptr;      /* A pointer to the beginning of the string table */
-  int *imports_ptr;      /* A pointer to the beginning of imports table    */
-  int *public_ptr;       /* A pointer to the beginning of publics table    */
-  char *code_ptr;        /* A pointer to the bytecode itself               */
-  int *global_ptr;       /* A pointer to the global area                   */
-  int code_size;         /* The size (in bytes) of code                    */
+  uint main_offset; /* offset of the function 'main'                        */
+  char *string_ptr; /* A pointer to the beginning of the string table */
+  int *imports_ptr; /* A pointer to the beginning of imports table    */
+  int *public_ptr;  /* A pointer to the beginning of publics table    */
+  char *code_ptr;   /* A pointer to the bytecode itself               */
+  int *global_ptr;  /* A pointer to the global area                   */
+  int code_size;    /* The size (in bytes) of code                    */
   uint stringtab_size;   /* The size (in bytes) of the string table        */
   uint global_area_size; /* The size (in words) of global area             */
   uint imports_number;   /* The number of imports                          */
diff --git a/byterun/regression/Dep.i b/byterun/regression/Dep.i
new file mode 100644
index 000000000..e0493b13d
--- /dev/null
+++ b/byterun/regression/Dep.i
@@ -0,0 +1,2 @@
+I,Std;
+F,f;
diff --git a/byterun/regression/Dep.lama b/byterun/regression/Dep.lama
new file mode 100644
index 000000000..22e955ccd
--- /dev/null
+++ b/byterun/regression/Dep.lama
@@ -0,0 +1 @@
+public fun f(a, b) { a + b }
diff --git a/byterun/regression/Test.lama b/byterun/regression/Test.lama
new file mode 100644
index 000000000..3312c90f9
--- /dev/null
+++ b/byterun/regression/Test.lama
@@ -0,0 +1,3 @@
+import Dep;
+
+f(1, 2)
diff --git a/byterun/src/module_manager.cpp b/byterun/src/module_manager.cpp
index f3ee5a88a..2967ddc11 100644
--- a/byterun/src/module_manager.cpp
+++ b/byterun/src/module_manager.cpp
@@ -1,3 +1,4 @@
+#include <iostream>
 extern "C" {
 #include "module_manager.h"
 #include "utils.h"
@@ -33,16 +34,23 @@ static ModuleManager manager;
 
 uint32_t mod_add_impl(Bytefile *bf, bool do_verification,
                       std::optional<const char *> name = std::nullopt) {
+#ifdef DEBUG_VERSION
+  std::cerr << "- add module (impl) '" << std::string{name ? *name : ""}
+            << "'\n";
+#endif
   uint32_t id = manager.modules.size();
   manager.modules.push_back({.name = name ? *name : "", .bf = bf});
   for (size_t i = 0; i < bf->public_symbols_number; ++i) {
-    if (!manager.public_symbols_mods
-             .insert({
-                 get_public_name_safe(bf, i),
-                 {.mod_id = id, .offset = get_public_offset_safe(bf, i)},
-             })
-             .second) {
-      failure("public symbol loaded more then once\n");
+    const char *public_name = get_public_name_safe(bf, i);
+    size_t public_offset = get_public_offset_safe(bf, i);
+    if (strcmp(public_name, "main") == 0) {
+      bf->main_offset = public_offset;
+    } else if (!manager.public_symbols_mods
+                    .insert(
+                        {public_name, {.mod_id = id, .offset = public_offset}})
+                    .second) {
+      failure("public symbol '%s' loaded more then once\n",
+              get_public_name_safe(bf, i));
     }
   }
   if (name) {
@@ -56,8 +64,11 @@ uint32_t mod_add_impl(Bytefile *bf, bool do_verification,
 
 uint32_t path_mod_load(const char *name, std::filesystem::path &&path,
                        bool do_verification) {
+#ifdef DEBUG_VERSION
+  std::cerr << "- module path load '" << name << "'\n";
+#endif
   Bytefile *module = read_file(path.c_str());
-  return mod_add_impl(module, name);
+  return mod_add_impl(module, do_verification, name);
 }
 extern "C" {
 
@@ -114,6 +125,9 @@ int32_t mod_load(const char *name, bool do_verification) {
 }
 
 uint32_t mod_add(Bytefile *module, bool do_verification) {
+#ifdef DEBUG_VERSION
+  std::cerr << "- add module, no name\n";
+#endif
   return mod_add_impl(module, do_verification);
 }
 
diff --git a/byterun/src/parser.cpp b/byterun/src/parser.cpp
index 67ebf13be..858a1b430 100644
--- a/byterun/src/parser.cpp
+++ b/byterun/src/parser.cpp
@@ -52,7 +52,15 @@ Bytefile *read_file(const char *fname) {
   }
 
   long size = ftell(f);
-  long additional_size = sizeof(void *) * 5 + sizeof(int);
+
+  // [uint] stringtab_size
+  // [uint] global_area_size
+  // [uint] imports_number
+  // [uint] public_symbols_number
+  // char[0] buffer
+  long file_header_size = 4 * sizeof(uint) + sizeof(char[0]);
+
+  long additional_size = sizeof(Bytefile) - file_header_size;
   file = (Bytefile *)malloc(size +
                             additional_size); // file itself + additional data
 
diff --git a/byterun/src/types.c b/byterun/src/types.c
index 16e379ef5..0337d6c07 100644
--- a/byterun/src/types.c
+++ b/byterun/src/types.c
@@ -54,8 +54,8 @@ void init_mod_state(uint mod_id, struct State* s) {
 
   s->fp = NULL;
 
-  s->ip = s->bf->code_ptr;
-  s->instr_ip = s->bf->code_ptr;
+  s->ip = s->bf->code_ptr + s->bf->main_offset;
+  s->instr_ip = s->ip;
 
 #ifdef DEBUG_VERSION
   print_stack(s);