diff --git a/src/approxeq.rs b/src/approxeq.rs
index ccd173a0..591ad424 100644
--- a/src/approxeq.rs
+++ b/src/approxeq.rs
@@ -7,6 +7,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use std::num::Float;
 
 /// Trait for testing approximate equality
 pub trait ApproxEq<Eps> {
@@ -44,4 +45,4 @@ impl ApproxEq<f64> for f64 {
     fn approx_eq_eps(&self, other: &f64, approx_epsilon: &f64) -> bool {
         (*self - *other).abs() < *approx_epsilon
     }
-}
\ No newline at end of file
+}
diff --git a/src/length.rs b/src/length.rs
index 1185fb08..19927e1a 100644
--- a/src/length.rs
+++ b/src/length.rs
@@ -10,7 +10,7 @@
 
 use scale_factor::ScaleFactor;
 
-use std::num::{cast, Zero};
+use std::num::{NumCast, cast, Zero};
 
 /// A one-dimensional distance, with value represented by `T` and unit of measurement `Unit`.
 ///
diff --git a/src/point.rs b/src/point.rs
index 67730a60..3574dc7c 100644
--- a/src/point.rs
+++ b/src/point.rs
@@ -11,7 +11,7 @@ use length::Length;
 use size::Size2D;
 
 use std::fmt;
-use std::num::Zero;
+use std::num::{NumCast, Zero};
 
 #[deriving(Clone, Decodable, Encodable, Eq, Hash, PartialEq)]
 pub struct Point2D<T> {
diff --git a/src/rect.rs b/src/rect.rs
index edc6c5bd..348f86e0 100644
--- a/src/rect.rs
+++ b/src/rect.rs
@@ -13,7 +13,7 @@ use point::Point2D;
 use size::Size2D;
 use std::cmp::{PartialEq, PartialOrd};
 use std::fmt;
-use std::num::Zero;
+use std::num::{NumCast, Zero};
 
 #[deriving(Clone, Decodable, Encodable, PartialEq)]
 pub struct Rect<T> {
diff --git a/src/scale_factor.rs b/src/scale_factor.rs
index 818c24fd..a010ccfe 100644
--- a/src/scale_factor.rs
+++ b/src/scale_factor.rs
@@ -8,7 +8,7 @@
 // except according to those terms.
 //! A type-checked scaling factor between units.
 
-use std::num::{cast, One};
+use std::num::{NumCast, cast, One};
 
 /// A scaling factor between two different units of measurement.
 ///
diff --git a/src/side_offsets.rs b/src/side_offsets.rs
index ee0cd4d6..bf84dffd 100644
--- a/src/side_offsets.rs
+++ b/src/side_offsets.rs
@@ -10,7 +10,7 @@
 //! A group of side offsets, which correspond to top/left/bottom/right for borders, padding,
 //! and margins in CSS.
 
-use std::num::Zero;
+use std::num::{Num, NumCast, Zero};
 
 /// A group of side offsets, which correspond to top/left/bottom/right for borders, padding,
 /// and margins in CSS.
diff --git a/src/size.rs b/src/size.rs
index ff9fb3f5..0025539f 100644
--- a/src/size.rs
+++ b/src/size.rs
@@ -11,7 +11,7 @@ use length::Length;
 
 use std::cmp::PartialEq;
 use std::fmt;
-use std::num::Zero;
+use std::num::{NumCast, Zero};
 
 #[deriving(Clone, Decodable, Encodable, PartialEq)]
 pub struct Size2D<T> {