diff --git a/Cargo.lock b/Cargo.lock
index d63586bc..864e0dcc 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -227,6 +227,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4885c1409b6936c4898e646ef58baf6ec54edaf6d8179f79df805a7b85b7cf3e"
 dependencies = [
  "alloy-rlp",
+ "borsh",
  "bytes",
  "cfg-if",
  "const-hex",
@@ -4649,6 +4650,7 @@ dependencies = [
  "ark-ff 0.3.0",
  "ark-ff 0.4.2",
  "ark-ff 0.5.0",
+ "borsh",
  "bytes",
  "fastrlp 0.3.1",
  "fastrlp 0.4.0",
diff --git a/crates/composable-cow/Cargo.toml b/crates/composable-cow/Cargo.toml
index ceb66cc6..f12a385e 100644
--- a/crates/composable-cow/Cargo.toml
+++ b/crates/composable-cow/Cargo.toml
@@ -14,7 +14,9 @@ description = "ComposableCoW keeper machinery: the conditional-order body and th
 workspace = true
 
 [dependencies]
-alloy-primitives.workspace = true
+# `borsh` supplies the `Address`/`B256`/`Bytes` borsh impls the body
+# derives against, byte-identical to the fields they replace.
+alloy-primitives = { workspace = true, features = ["borsh"] }
 alloy-sol-types.workspace = true
 borsh.workspace = true
 cowprotocol = { version = "0.2.0", default-features = false }
diff --git a/crates/composable-cow/src/body.rs b/crates/composable-cow/src/body.rs
index b5f6bf02..1ca8466c 100644
--- a/crates/composable-cow/src/body.rs
+++ b/crates/composable-cow/src/body.rs
@@ -7,19 +7,25 @@
 //! This body type is that tuple in wire form. The one non-obvious
 //! invariant: `static_input` is opaque; only the named handler parses
 //! it, so this crate never inspects its bytes.
+//!
+//! Borsh comes from `alloy-primitives`' own `borsh` feature, so no
+//! adapter is needed: `Address` and `B256` encode as their bare bytes
+//! and `Bytes` length-prefixed, leaving the wire byte-identical to the
+//! `[u8; 20]`/`[u8; 32]`/`Vec<u8>` these fields replaced.
 
+use alloy_primitives::{Address, B256, Bytes};
 use borsh::{BorshDeserialize, BorshSerialize};
 
 /// The conditional order body: `ConditionalOrderParams` in wire form.
 #[derive(BorshSerialize, BorshDeserialize, Clone, Debug, PartialEq, Eq)]
 pub struct ComposableBody {
     /// The `IConditionalOrder` handler that mints the tradeable order.
-    pub handler: [u8; 20],
+    pub handler: Address,
     /// Salt distinguishing otherwise-identical conditional orders.
-    pub salt: [u8; 32],
+    pub salt: B256,
     /// Handler-specific static input; opaque to everything but the
     /// named handler.
-    pub static_input: Vec<u8>,
+    pub static_input: Bytes,
 }
 
 #[cfg(test)]
@@ -28,9 +34,9 @@ mod tests {
 
     fn sample() -> ComposableBody {
         ComposableBody {
-            handler: [0xab; 20],
-            salt: [0xcd; 32],
-            static_input: vec![1, 2, 3, 4, 5],
+            handler: Address::repeat_byte(0xab),
+            salt: B256::repeat_byte(0xcd),
+            static_input: Bytes::from_static(&[1, 2, 3, 4, 5]),
         }
     }
 
@@ -47,11 +53,31 @@ mod tests {
     #[test]
     fn empty_static_input_round_trips() {
         let mut body = sample();
-        body.static_input = Vec::new();
+        body.static_input = Bytes::new();
         let bytes = borsh::to_vec(&body).expect("encode");
         assert_eq!(
             ComposableBody::try_from_slice(&bytes).expect("decode"),
             body
         );
     }
+
+    /// The alloy types must encode exactly as the raw arrays did: 20
+    /// bare handler bytes, 32 bare salt bytes, then a `u32`-length-
+    /// prefixed static input.
+    #[test]
+    fn wire_matches_the_raw_array_layout() {
+        let mut expected = Vec::new();
+        expected.extend_from_slice(&[0xab; 20]);
+        expected.extend_from_slice(&[0xcd; 32]);
+        expected.extend_from_slice(&5_u32.to_le_bytes());
+        expected.extend_from_slice(&[1, 2, 3, 4, 5]);
+        assert_eq!(borsh::to_vec(&sample()).expect("encode"), expected);
+    }
+
+    /// A truncated handler is a decode error, not a silent short read.
+    #[test]
+    fn truncated_input_fails_to_decode() {
+        let bytes = borsh::to_vec(&sample()).expect("encode");
+        assert!(ComposableBody::try_from_slice(&bytes[..10]).is_err());
+    }
 }