diff --git a/lunar_wave_vm/src/loader.rs b/lunar_wave_vm/src/loader.rs
index c831147..4828512 100644
--- a/lunar_wave_vm/src/loader.rs
+++ b/lunar_wave_vm/src/loader.rs
@@ -160,6 +160,7 @@ pub fn parse_inst (buf: [u8; 4]) -> Option <Inst>
 		0x4a => Inst::ForPrep (a, bx),
 		0x4e => Inst::SetList (a, b, c, k),
 		0x4f => Inst::Closure (a, bx),
+		0x50 => unimplemented! ("OP_VARARG"),
 		0x51 => Inst::VarArgPrep (a.into ()),
 		0x52 => Inst::ExtraArg (ax),
 		_ => return None,
diff --git a/lunar_wave_vm/src/state.rs b/lunar_wave_vm/src/state.rs
index 5fb9de0..9e09e97 100644
--- a/lunar_wave_vm/src/state.rs
+++ b/lunar_wave_vm/src/state.rs
@@ -82,7 +82,6 @@ fn lw_print (l: &mut State, num_args: usize) -> usize {
 		}
 	}
 	println! ("");
-	*l.reg_mut (0) = Value::from (1993);
 	1
 }
 
@@ -107,9 +106,39 @@ fn lw_string_format (l: &mut State, num_args: usize) -> usize {
 	1
 }
 
-fn lw_tonumber (l: &mut State, num_args: usize) -> usize {
-	assert_eq! (num_args, 1, "tonumber only implemented for 1 argument");
-	let output = match l.reg (0) {
+fn lw_table_concat (l: &mut State, num_args: usize) -> usize {
+	assert_eq! (num_args, 2);
+	
+	let s = {
+		let t = l.reg (0).as_table ().unwrap ().borrow ();
+		let joiner = l.reg (1).as_str ().unwrap ();
+		
+		let mut s = String::new ();
+		
+		for i in 0..t.length () {
+			if i > 0 {
+				s.push_str (joiner);
+			}
+			let x = t.get_int (i + 1);
+			s.push_str (&format! ("{}", x));
+		}
+		s
+	};
+	*l.reg_mut (0) = Value::from (s);
+	1
+}
+
+fn lw_table_pack (l: &mut State, num_args: usize) -> usize {
+	let mut v = vec! [];
+	for i in 0..num_args {
+		v.push (l.reg (u8::try_from (i).unwrap ()).clone ());
+	}
+	*l.reg_mut (0) = Value::from_iter (v.into_iter ());
+	1
+}
+
+fn tonumber (value: &Value) -> Value {
+	match value {
 		Value::Float (x) => Value::Float (*x),
 		Value::Integer (x) => Value::Integer (*x),
 		Value::String (x) => {
@@ -124,7 +153,12 @@ fn lw_tonumber (l: &mut State, num_args: usize) -> usize {
 			}
 		},
 		_ => Value::Nil,
-	};
+	}
+}
+
+fn lw_tonumber (l: &mut State, num_args: usize) -> usize {
+	assert_eq! (num_args, 1, "tonumber only implemented for 1 argument");
+	let output = tonumber (l.reg (0));
 	*l.reg_mut (0) = output;
 	1
 }
@@ -182,12 +216,18 @@ impl State {
 			("format", Value::RsFunc (lw_string_format)),
 		].into_iter ().map (|(k, v)| (k.to_string (), v));
 		
+		let table = [
+			("concat", Value::RsFunc (lw_table_concat)),
+			("pack", Value::RsFunc (lw_table_pack)),
+		].into_iter ().map (|(k, v)| (k.to_string (), v));
+		
 		let env = [
 			("arg", arg),
 			("io", Value::from_iter (io.into_iter ())),
 			("math", Value::from_iter (math.into_iter ())),
 			("print", Value::RsFunc (lw_print)),
 			("string", Value::from_iter (string.into_iter ())),
+			("table", Value::from_iter (table.into_iter ())),
 			("tonumber", Value::RsFunc (lw_tonumber)),
 		].into_iter ().map (|(k, v)| (k.to_string (), v));
 		
@@ -336,7 +376,7 @@ impl State {
 						});
 						
 						let num_args = if b == 0 {
-							self.top - a as usize
+							self.top - new_offset
 						}
 						else {
 							b - 1
@@ -385,7 +425,7 @@ impl State {
 					upvalues: new_upvalues,
 				});
 			},
-			Instruction::Concat (a, b) => {
+			Instruction::Concat (_a, _b) => {
 				unimplemented! ("OP_CONCAT")
 			},
 			Instruction::Div (a, b, c) => {
diff --git a/lunar_wave_vm/src/tests.rs b/lunar_wave_vm/src/tests.rs
index 5fbae5e..137bbdc 100644
--- a/lunar_wave_vm/src/tests.rs
+++ b/lunar_wave_vm/src/tests.rs
@@ -208,9 +208,30 @@ fn function_calls () {
 	
 	vm.eval ("print (x ())").ok ();
 	vm.eval ("x = function () return 5 end").ok ();
+	
+	// Currently failing because I don't have a way to jump into a Lua
+	// function that's no longer in the currently-executing chunk
 	vm.eval ("print (x ())").ok ();
 }
 
+#[test]
+fn function_returns () {
+	let upvalues = crate::State::upvalues_from_args (vec! ["_exe_name".to_string ()].into_iter ());
+	
+	let mut vm = crate::State::new (crate::Chunk::default (), upvalues);
+	
+	assert_eq! (
+		vm.eval ("return ((function () return 5 end)())").unwrap (), 
+		vec! [Value::from (5)]
+	);	
+	assert_eq! (
+		vm.eval ("return (math.sqrt (25))").unwrap (), 
+		vec! [Value::from (5.0)]
+	);
+	
+	
+}
+
 #[test]
 fn heap () {
 	use std::{