diff --git a/src/canvas.rs b/src/canvas.rs
index 55a6566..cb20a91 100644
--- a/src/canvas.rs
+++ b/src/canvas.rs
@@ -142,7 +142,7 @@ impl Canvas {
     /// negative coordinates will wrap around.
     pub fn get_mut(&mut self, x: i16, y: i16) -> &mut Module {
         let index = self.coords_to_index(x, y);
-        self.modules.get_mut(index)
+        self.modules.index_mut(&index)
     }
 
     /// Sets the color of a module at the given coordinates. For convenience,
@@ -185,7 +185,7 @@ mod basic_canvas_tests {
                     2 => Dark,
                     3 => LightUnmasked,
                     4 => DarkUnmasked,
-                    _ => fail!(),
+                    _ => panic!(),
                 });
             }
         }
@@ -1348,7 +1348,7 @@ impl Canvas {
                     LargeCheckerboard => 0b01,
                     Diamonds => 0b10,
                     Meadow => 0b11,
-                    _ => fail!("Unsupported mask pattern in Micro QR code"),
+                    _ => panic!("Unsupported mask pattern in Micro QR code"),
                 };
                 let symbol_number = match (a, self.ec_level) {
                     (1, L) => 0b000,
@@ -1359,7 +1359,7 @@ impl Canvas {
                     (4, L) => 0b101,
                     (4, M) => 0b110,
                     (4, Q) => 0b111,
-                    _ => fail!("Unsupported version/ec_level combination in Micro QR code"),
+                    _ => panic!("Unsupported version/ec_level combination in Micro QR code"),
                 };
                 let simple_format_number = symbol_number << 2 | micro_pattern_number;
                 FORMAT_INFOS_MICRO_QR[simple_format_number]
diff --git a/src/ec.rs b/src/ec.rs
index e47bbfd..3563344 100644
--- a/src/ec.rs
+++ b/src/ec.rs
@@ -8,7 +8,7 @@ use types::{QrResult, QrVersion, ErrorCorrectionLevel};
 /// Creates the error correction code in N bytes.
 ///
 /// This method only supports computing the error-correction code up to
-/// 69 bytes. Longer blocks will result in failure.
+/// 69 bytes. Longer blocks will result in task panic.
 ///
 /// This method treats the data as a polynomial of the form
 /// (a[0] x<sup>m+n</sup> + a[1] x<sup>m+n-1</sup> + … + a[m] x<sup>n</sup>) in
diff --git a/src/lib.rs b/src/lib.rs
index 7c82579..fa2bfa0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,7 +6,7 @@
 //!
 //!     let code = QrCode::new(b"Some content here.");
 //!     match code {
-//!         Err(err) => fail!("Failed to encode the QR code: {}", err),
+//!         Err(err) => panic!("Failed to encode the QR code: {}", err),
 //!         Ok(code) => {
 //!             for y in range(0, code.width()) {
 //!                 for x in range(0, code.width()) {
@@ -20,7 +20,7 @@
 
 #![unstable]
 #![feature(slicing_syntax)]
-#![feature(while_let)] 
+#![feature(while_let)]
 
 extern crate test;