diff --git a/ocamlrep_marshal/Cargo.toml b/ocamlrep_marshal/Cargo.toml
index 220039df..3c631e74 100644
--- a/ocamlrep_marshal/Cargo.toml
+++ b/ocamlrep_marshal/Cargo.toml
@@ -17,7 +17,7 @@ doctest = false
 crate-type = ["lib", "staticlib"]
 
 [dependencies]
-bitflags = "1.3"
+bitflags = "2.4"
 ocamlrep = { path = "../ocamlrep" }
 
 [build-dependencies]
diff --git a/ocamlrep_marshal/ser.rs b/ocamlrep_marshal/ser.rs
index 6ef2dc2b..0f0b8bf7 100644
--- a/ocamlrep_marshal/ser.rs
+++ b/ocamlrep_marshal/ser.rs
@@ -24,6 +24,7 @@ extern "C" {
 
 bitflags::bitflags! {
     /// Flags affecting marshaling
+    #[derive(PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Clone, Copy)]
     pub struct ExternFlags: u8 {
         /// Flag to ignore sharing
         const NO_SHARING = 1;
diff --git a/shim/third-party/rust/Cargo.toml b/shim/third-party/rust/Cargo.toml
index 426c1595..57f993e4 100644
--- a/shim/third-party/rust/Cargo.toml
+++ b/shim/third-party/rust/Cargo.toml
@@ -15,7 +15,7 @@ path = "top/main.rs"
 
 [dependencies]
 anyhow = "1.0.75"
-bitflags = "1.3"
+bitflags = "2.4"
 bstr = { version = "1.4.0", features = ["serde", "std", "unicode"] }
 bumpalo = { version = "3.14.0", features = ["allocator_api", "collections"] }
 clap-3 = { package = "clap", version = "3.2.25", features = ["derive", "env", "regex", "unicode", "wrap_help"] }