diff --git a/src/cgmath/lib.rs b/src/cgmath/lib.rs
index f97d4b6..edaee38 100644
--- a/src/cgmath/lib.rs
+++ b/src/cgmath/lib.rs
@@ -36,6 +36,8 @@
 //! `look_at`, `from_angle`, `from_euler`, and `from_axis_angle` methods.
 //! These are provided for convenience.
 
+extern crate debug;
+
 pub mod array;
 
 pub mod matrix;