diff --git a/Cargo.lock b/Cargo.lock
index 0f300ef995..92c3947b84 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4263,6 +4263,7 @@ dependencies = [
  "chrono",
  "clap",
  "contracts",
+ "derive_more",
  "ethcontract",
  "ethereum-types",
  "ethrpc",
diff --git a/crates/solvers/Cargo.toml b/crates/solvers/Cargo.toml
index 13826b32e2..be3693d0d3 100644
--- a/crates/solvers/Cargo.toml
+++ b/crates/solvers/Cargo.toml
@@ -17,6 +17,7 @@ axum = { workspace = true }
 bigdecimal = { version = "0.3", features = ["serde"] }
 chrono = { workspace = true, features = ["serde"], default-features = false }
 clap = { workspace = true, features = ["derive", "env"] }
+derive_more = { workspace = true }
 ethereum-types = { workspace = true }
 ethrpc = { path = "../ethrpc" }
 futures = { workspace = true }
diff --git a/crates/solvers/src/boundary/legacy.rs b/crates/solvers/src/boundary/legacy.rs
index f37ad1b066..9d1d00674e 100644
--- a/crates/solvers/src/boundary/legacy.rs
+++ b/crates/solvers/src/boundary/legacy.rs
@@ -437,7 +437,7 @@ fn to_domain_solution(
                     match order.solver_determines_fee() {
                         true => execution
                             .exec_fee_amount
-                            .map(solution::Fee::Surplus)
+                            .map(|fee| solution::Fee::Surplus(fee.into()))
                             .context("no surplus fee")?,
                         false => solution::Fee::Protocol,
                     },
diff --git a/crates/solvers/src/domain/eth/mod.rs b/crates/solvers/src/domain/eth/mod.rs
index 6aecdc1095..fab72882d3 100644
--- a/crates/solvers/src/domain/eth/mod.rs
+++ b/crates/solvers/src/domain/eth/mod.rs
@@ -1,5 +1,4 @@
-use {crate::util::bytes::Bytes, web3::types::AccessList};
-
+use {crate::util::bytes::Bytes, derive_more::From, web3::types::AccessList};
 mod chain;
 
 pub use {
@@ -45,6 +44,10 @@ impl From<U256> for Ether {
     }
 }
 
+/// A token amount in wei, always representing the sell token of an order.
+#[derive(Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd, From)]
+pub struct SellTokenAmount(pub U256);
+
 /// Like [`Gas`] but can be negative to encode a gas discount.
 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 pub struct SignedGas(i64);
diff --git a/crates/solvers/src/domain/solution.rs b/crates/solvers/src/domain/solution.rs
index 0ffa5815a1..4e1a0644ca 100644
--- a/crates/solvers/src/domain/solution.rs
+++ b/crates/solvers/src/domain/solution.rs
@@ -126,11 +126,7 @@ pub struct Single {
 impl Single {
     /// Creates a full solution for a single order solution given gas and sell
     /// token prices.
-    pub fn into_solution(
-        self,
-        gas_price: auction::GasPrice,
-        sell_token: auction::Price,
-    ) -> Option<Solution> {
+    pub fn into_solution(self, fee: eth::SellTokenAmount) -> Option<Solution> {
         let Self {
             order,
             input,
@@ -144,7 +140,7 @@ impl Single {
         }
 
         let fee = if order.solver_determines_fee() {
-            Fee::Surplus(sell_token.ether_value(eth::Ether(gas.0.checked_mul(gas_price.0 .0)?))?)
+            Fee::Surplus(fee)
         } else {
             Fee::Protocol
         };
@@ -299,7 +295,7 @@ pub enum Fee {
     Protocol,
 
     /// An additional surplus fee that is charged by the solver.
-    Surplus(U256),
+    Surplus(eth::SellTokenAmount),
 }
 
 impl Fee {
@@ -307,7 +303,7 @@ impl Fee {
     pub fn surplus(&self) -> Option<U256> {
         match self {
             Fee::Protocol => None,
-            Fee::Surplus(fee) => Some(*fee),
+            Fee::Surplus(fee) => Some(fee.0),
         }
     }
 }
diff --git a/crates/solvers/src/domain/solver/baseline.rs b/crates/solvers/src/domain/solver/baseline.rs
index d97e92ead2..5265afa9a4 100644
--- a/crates/solvers/src/domain/solver/baseline.rs
+++ b/crates/solvers/src/domain/solver/baseline.rs
@@ -189,6 +189,9 @@ impl Inner {
                 }
 
                 let gas = route.gas() + self.solution_gas_offset;
+                let fee = sell_token_price
+                    .ether_value(eth::Ether(gas.0.checked_mul(auction.gas_price.0 .0)?))?
+                    .into();
 
                 Some(
                     solution::Single {
@@ -198,7 +201,7 @@ impl Inner {
                         interactions,
                         gas,
                     }
-                    .into_solution(auction.gas_price, sell_token_price)?
+                    .into_solution(fee)?
                     .with_id(solution::Id(i as u64))
                     .with_buffers_internalizations(&auction.tokens),
                 )