diff --git a/src/geometry/orthographic.rs b/src/geometry/orthographic.rs
index ade84092..836edc93 100644
--- a/src/geometry/orthographic.rs
+++ b/src/geometry/orthographic.rs
@@ -18,6 +18,7 @@ use crate::base::{Matrix4, Vector, Vector3};
 use crate::geometry::{Point3, Projective3};
 
 /// A 3D orthographic projection stored as a homogeneous 4x4 matrix.
+#[repr(C)]
 pub struct Orthographic3<T: RealField> {
     matrix: Matrix4<T>,
 }
diff --git a/src/geometry/perspective.rs b/src/geometry/perspective.rs
index c7dd8b3e..08b2608b 100644
--- a/src/geometry/perspective.rs
+++ b/src/geometry/perspective.rs
@@ -19,6 +19,7 @@ use crate::base::{Matrix4, Scalar, Vector, Vector3};
 use crate::geometry::{Point3, Projective3};
 
 /// A 3D perspective projection stored as a homogeneous 4x4 matrix.
+#[repr(C)]
 pub struct Perspective3<T: Scalar> {
     matrix: Matrix4<T>,
 }