diff --git a/features/src/structs.rs b/features/src/structs.rs
index aefbde5..849d8ac 100644
--- a/features/src/structs.rs
+++ b/features/src/structs.rs
@@ -1,6 +1,9 @@
 use std::fmt;
 use std::ops;
 
+use num_traits::NumCast;
+use num_traits::cast;
+
 #[derive(Debug, Copy, Clone)]
 pub struct Tuple {
     x: f32,
@@ -9,13 +12,24 @@ pub struct Tuple {
     w: f32,
 }
 
+macro_rules! num_traits_cast {
+    ($tt:ident) => {
+        cast($tt).unwrap()
+    };
+}
+
 impl Tuple {
-    pub fn new<T: num_traits::NumCast>(x: T, y: T, z: T, w: T) -> Tuple {
+    pub fn new<X, Y, Z, W>(x: X, y: Y, z: Z, w: W) -> Tuple
+    where X: NumCast,
+    Y: NumCast,
+    Z: NumCast,
+    W: NumCast,
+     {
         Tuple {
-            x: num_traits::cast(x).unwrap(),
-            y: num_traits::cast(y).unwrap(),
-            z: num_traits::cast(z).unwrap(),
-            w: num_traits::cast(w).unwrap(),
+            x: num_traits_cast!(x),
+            y: num_traits_cast!(y),
+            z: num_traits_cast!(z),
+            w: num_traits_cast!(w),
         }
     }
 
@@ -28,20 +42,28 @@ impl Tuple {
         }
     }
 
-    pub fn point(x: f32, y: f32, z: f32) -> Tuple {
+    pub fn point<T, U, V>(x: T, y: U, z: V) -> Tuple
+    where T: NumCast,
+    U: NumCast,
+    V: NumCast,
+
+     {
         Tuple {
-            x,
-            y,
-            z,
+            x: num_traits_cast!(x),
+            y: num_traits_cast!(y),
+            z: num_traits_cast!(z),
             w: 1.0,
         }
     }
 
-    pub fn vector(x: f32, y: f32, z: f32) -> Tuple {
+    pub fn vector<X, Y, Z>(x: X, y: Y, z: Z) -> Tuple
+    where X: NumCast,
+    Y: NumCast,
+    Z: NumCast {
         Tuple {
-            x,
-            y,
-            z,
+            x: num_traits_cast!(x),
+            y: num_traits_cast!(y),
+            z: num_traits_cast!(z),
             w: 0.0,
         }
     }
@@ -427,9 +449,36 @@ mod tests {
 
      #[test]
      fn works_with_i32() {
-         let a = Tuple::new(1, 2, 3);
+         let a = Tuple::new(1, 2, 3, 0);
          assert_eq!(1.0, a.x());
          assert_eq!(2.0, a.y());
          assert_eq!(3.0, a.z());
      }
+
+     #[test]
+     fn works_with_mixed_types() {
+         let a = Tuple::new(1.1, 2.2, 3, 0);
+         assert_eq!(1.1, a.x());
+         assert_eq!(2.2, a.y());
+         assert_eq!(3.0, a.z());
+     }
+
+     #[test]
+     fn point_with_mixed_types() {
+         let a = Tuple::point(1.0, 2.2, 3);
+         assert_eq!(1.0, a.x());
+         assert_eq!(2.2, a.y());
+         assert_eq!(3.0, a.z());
+         assert_eq!(1.0, a.w());
+     }
+
+     #[test]
+     fn vector_with_mixed_types() {
+         let a = Tuple::vector(1.0, 2.2, 3);
+         assert_eq!(1.0, a.x());
+         assert_eq!(2.2, a.y());
+         assert_eq!(3.0, a.z());
+         assert_eq!(0.0, a.w());
+
+     }
 }