diff --git a/byterun/dep_check.sh b/byterun/dep_check.sh
index 76fad74d1..bccbeab48 100755
--- a/byterun/dep_check.sh
+++ b/byterun/dep_check.sh
@@ -10,17 +10,22 @@ compiler=../_build/default/src/Driver.exe
 echo "Used compiler path:"
 echo $compiler
 
-$compiler -b  regression/Dep.lama > /dev/null
+$compiler -b  regression/Dep.lama
+$compiler -b  -I regression/ regression/Dep2.lama
+
+$compiler -b  ../stdlib/List.lama
+$compiler -b  ../stdlib/Ref.lama
+$compiler -b  ../stdlib/Fun.lama
 
 for test in regression/dep_test*.lama; do 
   echo $test
-  $compiler -b  $test -I regression/ > /dev/null
+  $compiler -b  $test -I regression/
   test_file="${test%.*}"
   echo $test_file
-  cat $test_file.input | ./byterun.exe -vi dep_test*.bc > /dev/null
+  cat $test_file.input | ./byterun.exe -vi dep_test*.bc
   rm dep_test*.bc
   echo "done"
 done
 
-rm Dep.bc
+rm *.bc
 rm *.o
diff --git a/byterun/regression/Dep2.i b/byterun/regression/Dep2.i
new file mode 100644
index 000000000..445dc0b22
--- /dev/null
+++ b/byterun/regression/Dep2.i
@@ -0,0 +1,3 @@
+I,Std;
+F,f;
+F,g;
diff --git a/byterun/regression/Dep2.lama b/byterun/regression/Dep2.lama
new file mode 100644
index 000000000..7c678f2d7
--- /dev/null
+++ b/byterun/regression/Dep2.lama
@@ -0,0 +1,3 @@
+import Dep;
+
+public fun g(a, b) { a * b }
diff --git a/byterun/regression/dep_test002.input b/byterun/regression/dep_test002.input
new file mode 100644
index 000000000..e69de29bb
diff --git a/byterun/regression/dep_test002.lama b/byterun/regression/dep_test002.lama
new file mode 100644
index 000000000..32734d6de
--- /dev/null
+++ b/byterun/regression/dep_test002.lama
@@ -0,0 +1,3 @@
+import Dep2;
+
+f(1, 2)
diff --git a/byterun/regression/dep_test003.input b/byterun/regression/dep_test003.input
new file mode 100644
index 000000000..e69de29bb
diff --git a/byterun/regression/dep_test003.lama b/byterun/regression/dep_test003.lama
new file mode 100644
index 000000000..35e9e6ae1
--- /dev/null
+++ b/byterun/regression/dep_test003.lama
@@ -0,0 +1,4 @@
+import Fun;
+import List;
+
+write(fix (fun (f) {fun (n) {if n == 1 then 1 else n * f (n-1) fi}})(5))
diff --git a/byterun/src/interpreter.c b/byterun/src/interpreter.c
index 27bae6d11..e860e3ca4 100644
--- a/byterun/src/interpreter.c
+++ b/byterun/src/interpreter.c
@@ -82,13 +82,23 @@ void run_prepare_exec(int argc, char **argv) {
 
 void run_mod_rec(uint mod_id, int argc, char **argv, bool do_verification) {
   Bytefile* mod = mod_get(mod_id);
+#ifdef DEBUG_VERSION
+  printf("- run mod rec, %i imports\n", mod->imports_number);
+#endif
   for (size_t i = 0; i < mod->imports_number; ++i) {
-    if (find_mod_loaded(get_import_safe(mod, i)) < 0 && strcmp(get_import_safe(mod, i), "Std") != 0) { // not loaded
-      int32_t import_mod = mod_load(get_import_safe(mod, i), do_verification);
+    const char* import_str = get_import_safe(mod, i);
+    if (find_mod_loaded(import_str) < 0 && strcmp(import_str, "Std") != 0) { // not loaded
+#ifdef DEBUG_VERSION
+      printf("- mod load <%s>\n", import_str);
+#endif
+      int32_t import_mod = mod_load(import_str, do_verification);
       if (import_mod < 0) {
-        failure("module %s not found\n", get_import_safe(mod, i));
+        failure("module <%s> not found\n", import_str);
       }
-      run_mod_rec(mod_id, argc, argv, do_verification);
+#ifdef DEBUG_VERSION
+      printf("- mod run <%s>\n", import_str);
+#endif
+      run_mod_rec(import_mod, argc, argv, do_verification);
     }
   }
 
@@ -390,7 +400,7 @@ void run_mod(uint mod_id, int argc, char **argv) {
                   s.is_closure_call, args_sz, locals_sz);
 #ifdef WITH_CHECK
         if ((void **)__gc_stack_top + (aint)max_additional_stack_sz - 1 <= s.stack) {
-          s_failure(&s, "stack owerflow");
+          s_failure(&s, "stack overflow");
         }
 #endif
         break;
@@ -498,7 +508,7 @@ void run_mod(uint mod_id, int argc, char **argv) {
 
         struct ModSearchResult func = mod_search_pub_symbol(call_func_name);
         if (func.mod_file == NULL) {
-          failure("RUNTIME:ERROR: external function <%s> with <%zu> args not found\n", call_func_name, args_count);
+          failure("RUNTIME ERROR: external function <%s> with <%zu> args not found\n", call_func_name, args_count);
         }
 
         call_happened = true;
diff --git a/byterun/src/module_manager.cpp b/byterun/src/module_manager.cpp
index 0d2189885..1a9f66382 100644
--- a/byterun/src/module_manager.cpp
+++ b/byterun/src/module_manager.cpp
@@ -45,6 +45,9 @@ uint32_t mod_add_impl(Bytefile *bf, bool do_verification,
   manager.modules.push_back({.name = name ? *name : "", .bf = bf});
   for (size_t i = 0; i < bf->public_symbols_number; ++i) {
     const char *public_name = get_public_name_safe(bf, i);
+#ifdef DEBUG_VERSION
+    std::cerr << "- load public " << public_name << "\n";
+#endif
     size_t public_offset = get_public_offset_safe(bf, i);
     if (strcmp(public_name, "main") == 0) {
       bf->main_offset = public_offset;
diff --git a/byterun/src/parser.cpp b/byterun/src/parser.cpp
index b8c77b3d0..e50827351 100644
--- a/byterun/src/parser.cpp
+++ b/byterun/src/parser.cpp
@@ -44,11 +44,11 @@ Bytefile *read_file(const char *fname) {
   Bytefile *file;
 
   if (f == 0) {
-    failure("%s\n", strerror(errno));
+    failure("read file %s: %s\n", fname, strerror(errno));
   }
 
   if (fseek(f, 0, SEEK_END) == -1) {
-    failure("%s\n", strerror(errno));
+    failure("read file %s: %s\n", fname, strerror(errno));
   }
 
   long size = ftell(f);