diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 97649afc2..83421282b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -182,6 +182,8 @@ jobs:
             test_name: alice_broken_wallet_rpc_after_started_btc_early_refund
           - package: swap
             test_name: happy_path_alice_does_not_send_transfer_proof
+          - package: swap
+            test_name: bob_xmr_validation
           - package: monero-tests
             test_name: reserve_proof
           - package: monero-tests
diff --git a/swap/tests/bob_xmr_validation.rs b/swap/tests/bob_xmr_validation.rs
new file mode 100644
index 000000000..7ab3d235b
--- /dev/null
+++ b/swap/tests/bob_xmr_validation.rs
@@ -0,0 +1,176 @@
+pub mod harness;
+
+use swap::asb::FixedRate;
+use swap::protocol::alice::AliceState;
+use swap::protocol::bob::BobState;
+use swap::protocol::{alice, bob};
+use swap_core::monero::Amount;
+
+use crate::harness::SlowCancelConfig;
+
+#[tokio::test]
+async fn given_alice_locks_wrong_xmr_amount_bob_rejects() {
+    harness::setup_test(SlowCancelConfig, None, |mut ctx| async move {
+        // Run Bob until he finds a swap candidate
+        let (bob_swap, bob_join_handle) = ctx.bob_swap().await;
+        let bob_swap_id = bob_swap.id;
+        let bob_swap = tokio::spawn(bob::run_until(bob_swap, |s| {
+            matches!(s, BobState::XmrLockTransactionCandidate { .. })
+        }));
+
+        // Run until Alice detects the Bitcoin as having been locked
+        let alice_swap = ctx.alice_next_swap().await;
+
+        let alice_state = alice::run_until(
+            alice_swap,
+            |s| matches!(s, AliceState::BtcLocked { .. }),
+            FixedRate::default(),
+        )
+        .await?;
+
+
+        // Resume Alice such that she locks the wrong amount of Monero
+        ctx.restart_alice().await;
+        let mut alice_swap = ctx.alice_next_swap().await;
+
+        // Modify Alice such that she locks the wrong amount of Monero
+        alice_swap.state = alice_state.lower_by_one_piconero();
+        let alice_swap = tokio::spawn(alice::run(alice_swap, FixedRate::default()));
+
+        // Assert that Bob recognises Alice as a swap candidate
+        let bob_state = bob_swap.await??;
+        assert!(matches!(
+            bob_state,
+            BobState::XmrLockTransactionCandidate { .. }
+        ));
+
+        // Resume Bob and wait run until Bob detects the problem
+        let (bob_swap, bob_join_handle) = ctx
+            .stop_and_resume_bob_from_db(bob_join_handle, bob_swap_id)
+            .await;
+        let bob_state =
+            bob::run_until(bob_swap, 
+                |s| matches!(s, BobState::WaitingForCancelTimelockExpiration { .. })
+            ).await?;
+        
+        // Assert that Bob detects the problem
+        assert!(matches!(
+            bob_state,
+            BobState::WaitingForCancelTimelockExpiration { .. }
+        ));
+
+        // Resume Bob and wait till completion
+        let (bob_swap, bob_join_handle) = ctx
+            .stop_and_resume_bob_from_db(bob_join_handle, bob_swap_id)
+            .await;
+        let bob_state =
+            bob::run_until(bob_swap, |s| matches!(s, BobState::BtcRefunded(..))).await?;
+
+        // Assert that both Bob and Alice refunded
+        ctx.assert_bob_refunded(bob_state).await;
+        let alice_state = alice_swap.await??;
+        ctx.assert_alice_refunded(alice_state).await;
+
+
+        Ok(())
+    })
+    .await;
+}
+
+#[tokio::test]
+async fn given_significantly_wrong_xmr_amount_bob_immediately_aborts() {
+    harness::setup_test(SlowCancelConfig, None, |mut ctx| async move {
+        // Run Bob until he finds a swap candidate
+        let (bob_swap, bob_join_handle) = ctx.bob_swap().await;
+        let bob_swap_id = bob_swap.id;
+        let bob_swap = tokio::spawn(bob::run_until(bob_swap, |s| {
+            matches!(s, BobState::XmrLockTransactionCandidate { .. })
+        }));
+
+        // Run until Alice detects the Bitcoin as having been locked
+        let alice_swap = ctx.alice_next_swap().await;
+
+        let alice_state = alice::run_until(
+            alice_swap,
+            |s| matches!(s, AliceState::BtcLocked { .. }),
+            FixedRate::default(),
+        )
+        .await?;
+
+
+        // Resume Alice such that she locks half the amount
+        ctx.restart_alice().await;
+        let mut alice_swap = ctx.alice_next_swap().await;
+
+        // Modify Alice such that she locks half the amount
+        alice_swap.state = alice_state.lower_by_one_piconero();
+        let alice_swap = tokio::spawn(alice::run(alice_swap, FixedRate::default()));
+
+        // Assert that Bob recognises Alice as a swap candidate
+        let bob_state = bob_swap.await??;
+        assert!(matches!(
+            bob_state,
+            BobState::XmrLockTransactionCandidate { .. }
+        ));
+
+        // Resume Bob and wait run until Bob detects the problem
+        let (bob_swap, bob_join_handle) = ctx
+            .stop_and_resume_bob_from_db(bob_join_handle, bob_swap_id)
+            .await;
+        let bob_state =
+            bob::run_until(bob_swap, 
+                |s| matches!(s, BobState::WaitingForCancelTimelockExpiration { .. })
+            ).await?;
+        
+        // Assert that Bob detects the problem
+        assert!(matches!(
+            bob_state,
+            BobState::WaitingForCancelTimelockExpiration { .. }
+        ));
+
+        // Resume Bob and wait till completion
+        let (bob_swap, bob_join_handle) = ctx
+            .stop_and_resume_bob_from_db(bob_join_handle, bob_swap_id)
+            .await;
+        let bob_state =
+            bob::run_until(bob_swap, |s| matches!(s, BobState::BtcRefunded(..))).await?;
+
+        // Assert that both Bob and Alice refunded
+        ctx.assert_bob_refunded(bob_state).await;
+        let alice_state = alice_swap.await??;
+        ctx.assert_alice_refunded(alice_state).await;
+
+
+        Ok(())
+    })
+    .await;
+}
+
+trait FakeModifyMoneroAmount {
+    /// Reduces the Monero amount by one piconero
+    fn lower_by_one_piconero(self) -> Self;
+    // Halves the Monero amount
+    fn halve_xmr_amount(self) -> Self;
+}
+
+impl FakeModifyMoneroAmount for AliceState {
+    fn lower_by_one_piconero(self) -> Self {
+        let AliceState::BtcLocked { mut state3 } = self else {
+            panic!("Expected BtcLocked state to be able to modify the Monero amount");
+        };
+
+        let one_piconero = Amount::from_piconero(1);
+
+        state3.xmr = state3.xmr.checked_sub(one_piconero).unwrap();
+
+        Self::BtcLocked { state3 }
+    }
+
+    fn halve_xmr_amount(self) -> Self {
+        let AliceState::BtcLocked { mut state3 } = self else {
+            panic!("Expected BtcLocked state to be able to modify the Monero amount");
+        };
+        state3.xmr = Amount::from_piconero(state3.xmr.as_piconero() / 2);
+        Self::BtcLocked { state3 }
+    }
+}