diff --git a/lang/src/main.asm b/lang/src/main.asm
index b244aa9..22112be 100644
--- a/lang/src/main.asm
+++ b/lang/src/main.asm
@@ -1,7 +1,6 @@
 ;; Compile with:
 ;; nasm -f elf64 main.asm -o main.o
 
-;; RO section
 section .data
     hello_msg db "Hello, World!", 10
     hello_msg_len equ $ - hello_msg
@@ -32,7 +31,10 @@ _start:
     mov rdx, rax          ; filename pointer
     call fopen_read
     mov rax, 42
-    ret
+    ; exit with success
+    mov rdi, 0           ; status:
+    mov rax, 60          ; syscall: exit
+    syscall
 
 .no_filename:
     call die
@@ -54,9 +56,7 @@ die:
 ;; Writes a string to stderr:
 ;; rdx: pointer to string
 ;; rcx: length of string
-eprint_str:                      ; print string-length pair to stderr
-    ; str pointer in rdx
-    ; length in rcx
+eprint_str:
     mov rax, 1           ; syscall: write
     mov rdi, 2           ; fd: stderr
     mov rsi, rdx         ; buf: str
@@ -93,7 +93,7 @@ memcpy:
     ret
 
 ;; Opens file for reading:
-    ;; rdx: pointer to filename (null-terminated)
+;; rdx: pointer to filename (null-terminated)
 fopen_read:
     mov rax, 2           ; syscall: open
     mov rdi, rdx         ; filename
@@ -103,42 +103,43 @@ fopen_read:
     cmp rax, 0
     jl .file_error
     ret                         ;fd in rax
+
 .file_error:
-    ; allocate stack space for error message
     mov rdx, rdi                ; filename is in rdi
     call strlen                 ; get length of filename
-    mov r9, rax
+    mov r9, rax                 ; r9 = filename length
+
     mov rsi, r9
-    add rsi, file_error_msg_len ; add length of error message prefix
-    add rsi, 1                  ; for new line
-    ; align to 16 bytes
+    add rsi, file_error_msg_len ; + prefix
+    add rsi, 1                  ; + newline
     add rsi, 15
-    and rsi, -16                
-    sub rsp, rsi ; alloca
-    push rsi ; save length for dealloca
+    and rsi, -16                ; align up to 16
+    sub rsp, rsi                ; allocate buffer
+    push rsi                    ; save allocation size
+
     ; copy file_error_msg
     lea rdx, [rsp + 8]
     mov rcx, file_error_msg
     mov r8, file_error_msg_len
     call memcpy
+
     ; copy filename
     lea rdx, [rsp + 8 + file_error_msg_len]
     mov rcx, rdi
     mov r8, r9
     call memcpy
+
     ; trailing newline
     lea rdx, [rsp + 8 + file_error_msg_len + r9]
     mov byte [rdx], 10
+
     ; print error message
     lea rdx, [rsp + 8]
-    mov rcx, r9
-    add rcx, file_error_msg_len
-    add rcx, 1
+    mov rcx, file_error_msg_len
+    add rcx, r9
+    add rcx, 1                  ; include newline
     call eprint_str
+
     pop rsi
-    add rsp, rsi ; dealloca
+    add rsp, rsi                ; dealloc
     ret
-    
-
-
-