diff --git a/rtchallenge/src/lib.rs b/rtchallenge/src/lib.rs
index 58b9c78..303381b 100644
--- a/rtchallenge/src/lib.rs
+++ b/rtchallenge/src/lib.rs
@@ -1,3 +1,6 @@
 pub mod canvas;
 pub mod matrices;
 pub mod tuples;
+
+/// Value considered close enough for PartialEq implementations.
+pub const EPSILON: f32 = 0.00001;
diff --git a/rtchallenge/src/tuples.rs b/rtchallenge/src/tuples.rs
index 46379de..4f798be 100644
--- a/rtchallenge/src/tuples.rs
+++ b/rtchallenge/src/tuples.rs
@@ -1,5 +1,7 @@
 use std::ops::{Add, Div, Mul, Neg, Sub};
 
+use crate::EPSILON;
+
 #[derive(Debug, Copy, Clone)]
 pub struct Tuple {
     pub x: f32,
@@ -116,10 +118,10 @@ impl Sub for Tuple {
 
 impl PartialEq for Tuple {
     fn eq(&self, rhs: &Tuple) -> bool {
-        ((self.x - rhs.x).abs() < f32::EPSILON)
-            && ((self.y - rhs.y).abs() < f32::EPSILON)
-            && ((self.z - rhs.z).abs() < f32::EPSILON)
-            && ((self.w - rhs.w).abs() < f32::EPSILON)
+        ((self.x - rhs.x).abs() < EPSILON)
+            && ((self.y - rhs.y).abs() < EPSILON)
+            && ((self.z - rhs.z).abs() < EPSILON)
+            && ((self.w - rhs.w).abs() < EPSILON)
     }
 }
 pub fn dot(a: Tuple, b: Tuple) -> f32 {
@@ -221,7 +223,7 @@ impl Sub for Color {
 
 #[cfg(test)]
 mod tests {
-    use super::{cross, dot, Color, Tuple};
+    use super::{cross, dot, Color, Tuple, EPSILON};
     #[test]
     fn is_point() {
         // A tuple with w = 1 is a point
@@ -326,7 +328,7 @@ mod tests {
     #[test]
     fn vector_normalize_magnitude() {
         let len = Tuple::vector(1., 2., 3.).normalize().magnitude();
-        assert!((1. - len).abs() < f32::EPSILON);
+        assert!((1. - len).abs() < EPSILON);
     }
     #[test]
     fn dot_two_tuples() {