diff --git a/src/nasal.h b/src/nasal.h
index c8ed818..2c548c1 100644
--- a/src/nasal.h
+++ b/src/nasal.h
@@ -18,7 +18,7 @@ using usize = std::size_t;
 using f64 = double;
 
 // virtual machine stack depth, both global depth and value stack depth
-const u32 VM_STACK_DEPTH = UINT16_MAX;
+const u32 VM_STACK_DEPTH = UINT16_MAX + 1;
 
 // avoid error loading function bug in MSVC version nasal.exe
 #ifdef _MSC_VER
diff --git a/src/nasal_vm.cpp b/src/nasal_vm.cpp
index 6884376..2e7e3f8 100644
--- a/src/nasal_vm.cpp
+++ b/src/nasal_vm.cpp
@@ -189,8 +189,7 @@ void vm::value_info(var& val) {
 }
 
 void vm::function_detail_info(const nas_func& func) {
-    std::clog << "func@";
-    std::clog << std::hex << reinterpret_cast<u64>(&func) << std::dec;
+    std::clog << "func ";
 
     std::vector<std::string> argument_list = {};
     argument_list.resize(func.keys.size());
@@ -238,6 +237,7 @@ void vm::function_call_trace() {
         // | locals| ...              |
         // +-------+------------------+
         // | func  | function         | <-- i - 1 - prev_func->local_size - 1
+        // +-------+------------------+
         if (i + 1 <= top && i[0].is_addr() && i[1].is_ret()) {
             auto r_addr = i[1].ret();
             callsite.push_back(r_addr);