diff --git a/Cargo.toml b/Cargo.toml
index 9e40f5a..ac17b08 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,6 +6,7 @@ repository = "https://github.com/seanyoung/cir"
 edition = "2021"
 description = "Linux Infrared Tooling"
 license = "MIT"
+rust-version = "1.70.0"
 exclude = [ "/.git*", "/testdata", "/tests" ]
 
 [dependencies]
diff --git a/irp/Cargo.toml b/irp/Cargo.toml
index fbe0506..c4def2d 100644
--- a/irp/Cargo.toml
+++ b/irp/Cargo.toml
@@ -9,7 +9,7 @@ documentation = "https://docs.rs/irp/"
 keywords = [ "IRP", "IR", "infrared", "pronto" ]
 readme = "README.md"
 license = "MIT"
-rust-version = "1.67.0"
+rust-version = "1.68.0"
 exclude = [ "/doc", "/tests" ]
 
 [dependencies]
diff --git a/irp/src/build_nfa.rs b/irp/src/build_nfa.rs
index f157c65..3622b85 100644
--- a/irp/src/build_nfa.rs
+++ b/irp/src/build_nfa.rs
@@ -20,7 +20,7 @@ pub(crate) struct Edge {
 }
 
 #[derive(PartialEq, Debug, Hash, Eq, Clone)]
-pub enum Length {
+pub(crate) enum Length {
     Expression(Rc<Expression>),
     Range(u32, u32),
 }