diff --git a/src/codegen_x86_64.rs b/src/codegen_x86_64.rs
index a92935e..547587d 100644
--- a/src/codegen_x86_64.rs
+++ b/src/codegen_x86_64.rs
@@ -77,12 +77,14 @@ pub struct CodegenX86_64<'a> {
     data_counter: usize,
     pub symbol_table: &'a SymbolTable,
     pub expr_types: &'a HashMap<usize, String>,
+    emit_debug: bool,
 }
 
 impl<'a> CodegenX86_64<'a> {
     pub fn new(
         symbol_table: &'a SymbolTable,
         expr_types: &'a HashMap<usize, String>,
+        emit_debug: bool,
     ) -> CodegenX86_64<'a> {
         CodegenX86_64 {
             output: String::new(),
@@ -91,6 +93,7 @@ impl<'a> CodegenX86_64<'a> {
             data_counter: 1,
             symbol_table,
             expr_types,
+            emit_debug,
         }
     }
 
@@ -344,11 +347,15 @@ _builtin_environ:
                 body,
                 exported,
             } => {
-                if *exported || name.lexeme == "main" {
-                    emit!(&mut self.output, "global {}", name.lexeme);
+                let name = &name.lexeme;
+                if self.emit_debug || *exported || name == "main" {
+                    emit!(
+                        &mut self.output,
+                        "global {name}:function (__end_{name} - {name})",
+                    );
                 }
-                emit!(&mut self.output, "section .text.{}", name.lexeme);
-                emit!(&mut self.output, "{}:", name.lexeme);
+                emit!(&mut self.output, "section .text.{}", name);
+                emit!(&mut self.output, "{}:", name);
                 emit!(&mut self.output, "    push rbp");
                 emit!(&mut self.output, "    mov rbp, rsp");
 
@@ -398,6 +405,10 @@ _builtin_environ:
                     emit!(&mut self.output, "    ret");
                 }
 
+                if self.emit_debug || *exported || name == "main" {
+                    emit!(&mut self.output, "__end_{}:", name);
+                }
+
                 // patch the stack size after we know how much we actually need
                 let patch = format!("    sub rsp, {:<10}", (env.next_offset + 15) & !15);
                 self.output
diff --git a/src/main.rs b/src/main.rs
index cc10322..161a605 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -54,7 +54,8 @@ fn compile_file(args: Args) -> Result<(), ZernError> {
         typechecker.typecheck_stmt(&mut typechecker::Env::new(), stmt)?;
     }
 
-    let mut codegen = codegen_x86_64::CodegenX86_64::new(&symbol_table, &typechecker.expr_types);
+    let mut codegen =
+        codegen_x86_64::CodegenX86_64::new(&symbol_table, &typechecker.expr_types, args.emit_debug);
     codegen.emit_prologue(args.use_crt)?;
     for stmt in statements {
         codegen.compile_stmt(&mut codegen_x86_64::Env::new(), &stmt)?;
@@ -63,19 +64,18 @@ fn compile_file(args: Args) -> Result<(), ZernError> {
     if !args.emit_only {
         let out = args.out.unwrap_or_else(|| "out".into());
 
-        fs::write(format!("{}.s", out), codegen.get_output()).unwrap();
+        fs::write(format!("{out}.s"), codegen.get_output()).unwrap();
 
-        run_command(format!("nasm -f elf64 -o {}.o {}.s", out, out));
+        run_command(format!("nasm -f elf64 -o {out}.o {out}.s"));
 
         if args.use_crt {
             run_command(format!(
-                "cc -no-pie -o {} {}.o -flto -Wl,--gc-sections {}",
-                out, out, args.cflags
+                "cc -no-pie -o {out} {out}.o -flto -Wl,--gc-sections {}",
+                args.cflags
             ));
         } else {
             run_command(format!(
-                "ld -static -o {} {}.o --gc-sections -e _start",
-                out, out
+                "ld -static -o {out} {out}.o --gc-sections -e _start"
             ));
         }
 
@@ -113,6 +113,7 @@ struct Args {
     path: String,
     out: Option<String>,
     emit_only: bool,
+    emit_debug: bool,
     include_stdlib: bool,
     run_exe: bool,
     use_crt: bool,
@@ -127,6 +128,7 @@ impl Args {
             path: String::new(),
             out: None,
             emit_only: false,
+            emit_debug: false,
             include_stdlib: true,
             run_exe: false,
             use_crt: false,
@@ -150,6 +152,8 @@ impl Args {
                 out.run_exe = true;
             } else if arg == "-m" {
                 out.use_crt = true;
+            } else if arg == "-g" {
+                out.emit_debug = true;
             } else if arg == "-C" {
                 match args.next() {
                     Some(s) => out.cflags = s,
@@ -160,16 +164,16 @@ impl Args {
                 }
             } else if arg == "-h" || arg == "--help" {
                 println!(
-                    "Usage: zern [-o path] [-r] [-m] [-C cflags] [--emit-only] [--no-stdlib] path"
+                    "Usage: zern [-o path] [-r] [-m] [-g] [-C cflags] [--emit-only] [--no-stdlib] path"
                 );
                 process::exit(0);
             } else if arg.starts_with('-') {
-                eprintln!("\x1b[91mERROR\x1b[0m: unrecognized option: {}", arg);
+                eprintln!("\x1b[91mERROR\x1b[0m: unrecognized option: {arg}");
                 process::exit(1);
             } else if out.path.is_empty() {
                 out.path = arg
             } else {
-                eprintln!("\x1b[91mERROR\x1b[0m: unrecognized argument: {}", arg);
+                eprintln!("\x1b[91mERROR\x1b[0m: unrecognized argument: {arg}");
                 process::exit(1);
             }
         }
diff --git a/src/std/std.zr b/src/std/std.zr
index 4073f71..286b8a7 100644
--- a/src/std/std.zr
+++ b/src/std/std.zr
@@ -495,9 +495,6 @@ func str.find[haystack: str, needle: str] : i64
     return -1
 
 func str.substr[s: str, start: i64, length: i64] : str
-    if start < 0 || length < 0 || start + length > str.len(s)
-        panic("str.substr out of bounds")
-
     out := mem.alloc(length + 1) as str
     mem.copy(s as ptr + start, out as ptr, length)
     out[length] = 0
@@ -1038,6 +1035,12 @@ func os.exit[code: i64] : void
 func os.getpid[] : i64
     return _builtin_syscall(SYS_getpid)
 
+func os.basename[path: str] : str
+    i := path->len() - 1
+    while i >= 0 && path[i] != '/'
+        i -= 1
+    return path->substr(i + 1, path->len() - i - 1)
+
 struct os.Timespec
     tv_sec: i64
     tv_nsec: i64
diff --git a/src/tokenizer.rs b/src/tokenizer.rs
index a4f3cac..a5a4322 100644
--- a/src/tokenizer.rs
+++ b/src/tokenizer.rs
@@ -260,7 +260,7 @@ impl Tokenizer {
                         break;
                     } else if self.peek() == '\n' {
                         self.loc.line += 1;
-                        self.loc.column = 1;
+                        self.loc.column = 0;
                     }
                     self.advance();
                 }