diff --git a/kurbo/src/axis.rs b/kurbo/src/axis.rs
index 758112e0..3c1efc93 100644
--- a/kurbo/src/axis.rs
+++ b/kurbo/src/axis.rs
@@ -5,6 +5,7 @@ use crate::{Point, Size, Vec2};
 
 /// An axis in the plane.
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
+#[repr(u8)]
 pub enum Axis {
     /// The x axis.
     Horizontal,
diff --git a/kurbo/src/cubicbez.rs b/kurbo/src/cubicbez.rs
index 1432f67f..ef3bab6e 100644
--- a/kurbo/src/cubicbez.rs
+++ b/kurbo/src/cubicbez.rs
@@ -46,6 +46,7 @@ struct ToQuads {
 
 /// Classification result for cusp detection.
 #[derive(Debug)]
+#[repr(u8)]
 pub enum CuspType {
     /// Cusp is a loop.
     Loop,
diff --git a/kurbo/src/simplify.rs b/kurbo/src/simplify.rs
index 9de24b43..21053cbf 100644
--- a/kurbo/src/simplify.rs
+++ b/kurbo/src/simplify.rs
@@ -64,6 +64,7 @@ pub struct SimplifyOptions {
 }
 
 /// Optimization level for simplification.
+#[repr(u8)]
 pub enum SimplifyOptLevel {
     /// Subdivide; faster but not as optimized results.
     Subdivide,
diff --git a/kurbo/src/stroke.rs b/kurbo/src/stroke.rs
index b13f448a..185758be 100644
--- a/kurbo/src/stroke.rs
+++ b/kurbo/src/stroke.rs
@@ -19,6 +19,7 @@ use crate::{
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[repr(u8)]
 pub enum Join {
     /// A straight line connecting the segments.
     Bevel,
@@ -32,6 +33,7 @@ pub enum Join {
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[repr(u8)]
 pub enum Cap {
     /// Flat cap.
     Butt,
@@ -76,6 +78,7 @@ pub struct StrokeOpts {
 /// should set it appropriately. For real time rendering, the appropriate
 /// value is `Subdivide`.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[repr(u8)]
 pub enum StrokeOptLevel {
     /// Adaptively subdivide segments in half.
     Subdivide,