diff --git a/src/bits.rs b/src/bits.rs
index 891f677..b798f35 100644
--- a/src/bits.rs
+++ b/src/bits.rs
@@ -758,7 +758,7 @@ impl Bits {
         where I: Iterator<Item=Segment>
     {
         for segment in segments_iter {
-            let slice = data.slice(segment.begin, segment.end);
+            let slice = &data[segment.begin .. segment.end];
             try!(match segment.mode {
                 Mode::Numeric => self.push_numeric_data(slice),
                 Mode::Alphanumeric => self.push_alphanumeric_data(slice),
diff --git a/src/canvas.rs b/src/canvas.rs
index ec1f5d1..47bcd3e 100644
--- a/src/canvas.rs
+++ b/src/canvas.rs
@@ -20,7 +20,7 @@ use types::{Version, EcLevel};
 //{{{ Modules
 
 /// The color of a module (pixel) in the QR code.
-#[derive(PartialEq, Eq, Clone, Copy, Show)]
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
 pub enum Module {
     /// The module is empty.
     Empty,
@@ -177,8 +177,8 @@ mod basic_canvas_tests {
     fn test_debug_str() {
         let mut c = Canvas::new(Version::Normal(1), EcLevel::L);
 
-        for i in 3 .. 20 {
-            for j in 3 .. 20 {
+        for i in 3i16 .. 20 {
+            for j in 3i16 .. 20 {
                 c.put(i, j, match ((i * 3) ^ j) % 5 {
                     0 => Module::Empty,
                     1 => Module::Light,
@@ -1372,7 +1372,7 @@ 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.
-#[derive(Show, Copy)]
+#[derive(Debug, Copy)]
 pub enum MaskPattern {
     /// QR code pattern 000: `(x + y) % 2 == 0`.
     Checkerboard = 0b000,
@@ -1811,7 +1811,7 @@ mod penalty_tests {
         ];
 
         let mut c = Canvas::new(Version::Micro(4), EcLevel::Q);
-        for i in 0 .. 17 {
+        for i in 0i16 .. 17 {
             c.put(i, -1, HORIZONTAL_SIDE[i as usize]);
             c.put(-1, i, VERTICAL_SIDE[i as usize]);
         }
diff --git a/src/ec.rs b/src/ec.rs
index 5249744..3cf5234 100644
--- a/src/ec.rs
+++ b/src/ec.rs
@@ -31,7 +31,7 @@ pub fn create_error_correction_code(data: &[u8], ec_code_size: usize) -> Vec<u8>
         }
 
         let log_lead_coeff = LOG_TABLE[lead_coeff] as usize;
-        for (u, v) in res.slice_from_mut(i+1).iter_mut().zip(log_den.iter()) {
+        for (u, v) in res[i+1 ..].iter_mut().zip(log_den.iter()) {
             *u ^= EXP_TABLE[((*v as usize + log_lead_coeff) % 255) as usize];
         }
     }
diff --git a/src/optimize.rs b/src/optimize.rs
index c0d20ad..c67af38 100644
--- a/src/optimize.rs
+++ b/src/optimize.rs
@@ -11,7 +11,7 @@ use test::Bencher;
 //{{{ Segment
 
 /// A segment of data committed to an encoding mode.
-#[derive(PartialEq, Eq, Show, Copy, Clone)]
+#[derive(PartialEq, Eq, Debug, Copy, Clone)]
 pub struct Segment {
     /// The encoding mode of the segment of data.
     pub mode: Mode,
diff --git a/src/types.rs b/src/types.rs
index c03c2d4..c2bcba8 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -2,13 +2,14 @@
 
 use std::default::Default;
 use std::cmp::{PartialOrd, Ordering};
+use std::fmt::{Display, Formatter, Error};
 
 //------------------------------------------------------------------------------
 //{{{ QrResult
 
 /// `QrError` encodes the error encountered when generating a QR code.
 #[unstable]
-#[derive(Show, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum QrError {
     /// The data is too long to encode into a QR code for the given version.
     DataTooLong,
@@ -28,6 +29,19 @@ pub enum QrError {
     InvalidCharacter,
 }
 
+impl Display for QrError {
+    fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error> {
+        let msg = match *self {
+            QrError::DataTooLong => "data too long",
+            QrError::InvalidVersion => "invalid version",
+            QrError::UnsupportedCharacterSet => "unsupported character set",
+            QrError::InvalidEciDesignator => "invalid ECI designator",
+            QrError::InvalidCharacter => "invalid character",
+        };
+        fmt.write_str(msg)
+    }
+}
+
 /// `QrResult` is a convenient alias for a QR code generation result.
 #[stable]
 pub type QrResult<T> = Result<T, QrError>;
@@ -38,7 +52,7 @@ pub type QrResult<T> = Result<T, QrError>;
 
 /// The error correction level. It allows the original information be recovered
 /// even if parts of the code is damaged.
-#[derive(Show, PartialEq, Eq, Copy, Clone, PartialOrd, Ord)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone, PartialOrd, Ord)]
 #[unstable]
 pub enum EcLevel {
     /// Low error correction. Allows up to 7% of wrong blocks.
@@ -65,7 +79,7 @@ pub enum EcLevel {
 /// The smallest version is `Version::Normal(1)` of size 21×21, and the largest
 /// is `Version::Normal(40)` of size 177×177.
 #[unstable]
-#[derive(Show, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum Version {
     /// A normal QR code version. The parameter should be between 1 and 40.
     Normal(i16),
@@ -138,7 +152,7 @@ impl Version {
 
 /// The mode indicator, which specifies the character set of the encoded data.
 #[unstable]
-#[derive(Show, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum Mode {
     /// The data contains only characters 0 to 9.
     Numeric,