diff --git a/src/state.rs b/src/state.rs
index 3132012..4a40e19 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -444,6 +444,9 @@ impl <'a> State <'a> {
 				*self.reg_mut (*a) = (b % c).into ();
 			},
 			Instruction::Move (a, b) => {
+				// If the value in b is deleted instead of duplicated,
+				// a bunch of tests fail
+				
 				*self.reg_mut (*a) = self.reg (*b).clone ();
 			},
 			Instruction::Mul (a, b, c) => {
@@ -474,9 +477,10 @@ impl <'a> State <'a> {
 				
 				let popped_frame = self.stack.pop ().unwrap ();
 				
-				// Build closure if needed
-				if *k {
-					
+				// Build closure if needed. No point building if we're
+				// popping the last frame and exiting the program.
+				
+				if *k && ! self.stack.is_empty () {
 					let closure_idx = match &self.registers [popped_frame.register_offset + a] {
 						Value::BogusClosure (rc) => rc.borrow ().idx,
 						_ => panic! ("Impossible"),
diff --git a/src/value.rs b/src/value.rs
index c0ff740..7e8fdae 100644
--- a/src/value.rs
+++ b/src/value.rs
@@ -45,7 +45,7 @@ impl fmt::Debug for Value {
 			Value::Float (x) => write! (f, "{:?}", x),
 			Value::Integer (x) => write! (f, "{}", x),
 			Value::RsFunc (x) => write! (f, "function: {:?}", x),
-			Value::String (s) => write! (f, "{}", s),
+			Value::String (s) => write! (f, "\"{}\"", s),
 			Value::Table (t) => write! (f, "{:?}", t.borrow ()),
 			
 			Value::BogusClosure (x) => write! (f, "{:?}", x.borrow ()),
diff --git a/test_vectors/fma.lua b/test_vectors/fma.lua
index 9006a99..74c8d22 100644
--- a/test_vectors/fma.lua
+++ b/test_vectors/fma.lua
@@ -17,9 +17,10 @@ end
 local function run ()
 	local hh = fma (10, 11, 12)
 	print (hh)
+	return hh
 end
 
-run ()
+local hh = run ()
 print (ii)
 
 return hh