diff --git a/src/bits.rs b/src/bits.rs
index 2ad03c2..a7a2a51 100644
--- a/src/bits.rs
+++ b/src/bits.rs
@@ -142,6 +142,7 @@ fn bench_push_splitted_bytes(bencher: &mut Bencher) {
 
 /// An "extended" mode indicator, includes all indicators supported by QR code
 /// beyond those bearing data.
+#[deriving(Copy)]
 pub enum ExtendedMode {
     /// ECI mode indicator, to introduce an ECI designator.
     Eci,
diff --git a/src/canvas.rs b/src/canvas.rs
index 632e034..71da3bc 100644
--- a/src/canvas.rs
+++ b/src/canvas.rs
@@ -1276,7 +1276,7 @@ mod draw_codewords_test {
 
 /// The mask patterns. Since QR code and Micro QR code do not use the same
 /// pattern number, we name them according to their shape instead of the number.
-#[deriving(Show)]
+#[deriving(Show, Copy)]
 pub enum MaskPattern {
     /// QR code pattern 000: `(x + y) % 2 == 0`.
     Checkerboard = 0b000,
@@ -1492,10 +1492,10 @@ impl Canvas {
         let mut total_score = 0;
 
         for i in range(0, self.width) {
-            let map_fn = if is_horizontal {
-                |j| self.get(j, i)
+            let map_fn = |&:j| if is_horizontal {
+                self.get(j, i)
             } else {
-                |j| self.get(i, j)
+                self.get(i, j)
             };
 
             let mut colors = range(0, self.width).map(map_fn)
diff --git a/src/lib.rs b/src/lib.rs
index 5d1dde2..8e0218c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -20,7 +20,6 @@
 
 #![unstable]
 #![feature(slicing_syntax)]
-#![feature(while_let)]
 
 extern crate test;
 
diff --git a/src/optimize.rs b/src/optimize.rs
index 1ac8997..57fc86d 100644
--- a/src/optimize.rs
+++ b/src/optimize.rs
@@ -1,19 +1,17 @@
 #![unstable]
 
 //! Find the optimal data mode sequence to encode a piece of data.
-
-use std::slice::Items;
+use std::slice::Iter;
+use types::{Mode, Version};
 
 #[cfg(test)]
 use test::Bencher;
 
-use types::{Mode, Version};
-
 //------------------------------------------------------------------------------
 //{{{ Segment
 
 /// A segment of data committed to an encoding mode.
-#[deriving(PartialEq, Eq, Show)]
+#[deriving(PartialEq, Eq, Show, Copy, Clone)]
 pub struct Segment {
     /// The encoding mode of the segment of data.
     pub mode: Mode,
@@ -82,7 +80,7 @@ impl<'a, I: Iterator<&'a u8>> Iterator<(uint, ExclCharSet)> for EcsIter<I> {
 
 /// QR code data parser to classify the input into distinct segments.
 pub struct Parser<'a> {
-    ecs_iter: EcsIter<Items<'a, u8>>,
+    ecs_iter: EcsIter<Iter<'a, u8>>,
     state: State,
     begin: uint,
     pending_single_byte: bool,
@@ -467,6 +465,7 @@ fn bench_optimize(bencher: &mut Bencher) {
 /// All values of `u8` can be split into 9 different character sets when
 /// determining which encoding to use. This enum represents these groupings for
 /// parsing purpose.
+#[deriving(Copy)]
 enum ExclCharSet {
     /// The end of string.
     End = 0,
@@ -526,6 +525,7 @@ impl ExclCharSet {
 }
 
 /// The current parsing state.
+#[deriving(Copy)]
 enum State {
     /// Just initialized.
     Init = 0,
@@ -552,6 +552,7 @@ enum State {
 }
 
 /// What should the parser do after a state transition.
+#[deriving(Copy)]
 enum Action {
     /// The parser should do nothing.
     Idle,
diff --git a/src/types.rs b/src/types.rs
index 6abf9c0..5d4f8f1 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -7,7 +7,7 @@ use std::default::Default;
 
 /// `QrError` encodes the error encountered when generating a QR code.
 #[unstable]
-#[deriving(Show, PartialEq, Eq)]
+#[deriving(Show, PartialEq, Eq, Copy, Clone)]
 pub enum QrError {
     /// The data is too long to encode into a QR code for the given version.
     DataTooLong,
@@ -136,7 +136,7 @@ impl Version {
 
 /// The mode indicator, which specifies the character set of the encoded data.
 #[unstable]
-#[deriving(Show, PartialEq, Eq)]
+#[deriving(Show, PartialEq, Eq, Copy, Clone)]
 pub enum Mode {
     /// The data contains only characters 0 to 9.
     Numeric,