diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4d171e4..b85f91e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Improves the `fmt::Debug` impls for `Vector`, `Matrix`, `Point`, `Decomposed`,
   `Quaternion` and `Angle` to make them easier to derive, and have clearer
   formatting.
+- Marks vectors, points, matrices, and angles as `#[repr(C, packed)]`.
 
 ## [v0.7.0] - 2015-12-23
 
diff --git a/src/angle.rs b/src/angle.rs
index 71c7bec..403a887 100644
--- a/src/angle.rs
+++ b/src/angle.rs
@@ -28,10 +28,16 @@ use rust_num::traits::cast;
 use approx::ApproxEq;
 use num::BaseFloat;
 
-/// An angle, in radians
+/// An angle, in radians.
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
 #[derive(Copy, Clone, PartialEq, PartialOrd, RustcEncodable, RustcDecodable)]
 pub struct Rad<S> { pub s: S }
-/// An angle, in degrees
+/// An angle, in degrees.
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
 #[derive(Copy, Clone, PartialEq, PartialOrd, RustcEncodable, RustcDecodable)]
 pub struct Deg<S> { pub s: S }
 
diff --git a/src/matrix.rs b/src/matrix.rs
index ca908f2..f364072 100644
--- a/src/matrix.rs
+++ b/src/matrix.rs
@@ -35,16 +35,37 @@ use vector::{Vector, EuclideanVector};
 use vector::{Vector2, Vector3, Vector4};
 
 /// A 2 x 2, column major matrix
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable)]
-pub struct Matrix2<S> { pub x: Vector2<S>, pub y: Vector2<S> }
+pub struct Matrix2<S> {
+    pub x: Vector2<S>,
+    pub y: Vector2<S>,
+}
 
 /// A 3 x 3, column major matrix
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable)]
-pub struct Matrix3<S> { pub x: Vector3<S>, pub y: Vector3<S>, pub z: Vector3<S> }
+pub struct Matrix3<S> {
+    pub x: Vector3<S>,
+    pub y: Vector3<S>,
+    pub z: Vector3<S>,
+}
 
 /// A 4 x 4, column major matrix
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable)]
-pub struct Matrix4<S> { pub x: Vector4<S>, pub y: Vector4<S>, pub z: Vector4<S>, pub w: Vector4<S> }
+pub struct Matrix4<S> {
+    pub x: Vector4<S>,
+    pub y: Vector4<S>,
+    pub z: Vector4<S>,
+    pub w: Vector4<S>,
+}
 
 
 impl<S: BaseFloat> Matrix2<S> {
diff --git a/src/point.rs b/src/point.rs
index b5a2dd2..fbf21fd 100644
--- a/src/point.rs
+++ b/src/point.rs
@@ -30,12 +30,25 @@ use num::{BaseNum, BaseFloat};
 use vector::*;
 
 /// A point in 2-dimensional space.
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
 #[derive(PartialEq, Eq, Copy, Clone, Hash, RustcEncodable, RustcDecodable)]
-pub struct Point2<S> { pub x: S, pub y: S }
+pub struct Point2<S> {
+    pub x: S,
+    pub y: S,
+}
 
 /// A point in 3-dimensional space.
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
 #[derive(PartialEq, Eq, Copy, Clone, Hash, RustcEncodable, RustcDecodable)]
-pub struct Point3<S> { pub x: S, pub y: S, pub z: S }
+pub struct Point3<S> {
+    pub x: S,
+    pub y: S,
+    pub z: S,
+}
 
 
 impl<S: BaseNum> Point2<S> {
diff --git a/src/quaternion.rs b/src/quaternion.rs
index b249960..9151003 100644
--- a/src/quaternion.rs
+++ b/src/quaternion.rs
@@ -31,6 +31,9 @@ use vector::{Vector3, Vector, EuclideanVector};
 
 /// A [quaternion](https://en.wikipedia.org/wiki/Quaternion) in scalar/vector
 /// form.
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
 #[derive(Copy, Clone, Debug, PartialEq, RustcEncodable, RustcDecodable)]
 pub struct Quaternion<S> {
     pub s: S,
diff --git a/src/vector.rs b/src/vector.rs
index b9dc1aa..b7b9ed8 100644
--- a/src/vector.rs
+++ b/src/vector.rs
@@ -136,12 +136,42 @@ pub trait Vector: Copy + Clone where
 /// Dot product of two vectors.
 #[inline] pub fn dot<V: Vector>(a: V, b: V) -> V::Scalar { a.dot(b) }
 
+/// A 2-dimensional vector.
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
+#[derive(PartialEq, Eq, Copy, Clone, Hash, RustcEncodable, RustcDecodable)]
+pub struct Vector2<S> {
+    pub x: S,
+    pub y: S,
+}
+
+/// A 3-dimensional vector.
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
+#[derive(PartialEq, Eq, Copy, Clone, Hash, RustcEncodable, RustcDecodable)]
+pub struct Vector3<S> {
+    pub x: S,
+    pub y: S,
+    pub z: S,
+}
+
+/// A 4-dimensional vector.
+///
+/// This type is marked as `#[repr(C, packed)]`.
+#[repr(C, packed)]
+#[derive(PartialEq, Eq, Copy, Clone, Hash, RustcEncodable, RustcDecodable)]
+pub struct Vector4<S> {
+    pub x: S,
+    pub y: S,
+    pub z: S,
+    pub w: S,
+}
+
 // Utility macro for generating associated functions for the vectors
 macro_rules! impl_vector {
     ($VectorN:ident <$S:ident> { $($field:ident),+ }, $n:expr, $constructor:ident) => {
-        #[derive(PartialEq, Eq, Copy, Clone, Hash, RustcEncodable, RustcDecodable)]
-        pub struct $VectorN<S> { $(pub $field: S),+ }
-
         impl<$S> $VectorN<$S> {
             /// Construct a new vector, using the provided values.
             #[inline]