diff --git a/amm/src/sync.rs b/amm/src/sync.rs
index 957457e..4ac1ab7 100644
--- a/amm/src/sync.rs
+++ b/amm/src/sync.rs
@@ -1,4 +1,6 @@
-use amm_core::{read_vault_fungible_balances, PoolDefinition, MINIMUM_LIQUIDITY};
+use amm_core::{
+    assert_supported_fee_tier, read_vault_fungible_balances, PoolDefinition, MINIMUM_LIQUIDITY,
+};
 use nssa_core::{
     account::{AccountWithMetadata, Data},
     program::{AccountPostState, ChainedCall},
@@ -11,6 +13,7 @@ pub fn sync_reserves(
 ) -> (Vec<AccountPostState>, Vec<ChainedCall>) {
     let pool_def_data = PoolDefinition::try_from(&pool.account.data)
         .expect("Sync reserves: AMM Program expects a valid Pool Definition Account");
+    assert_supported_fee_tier(pool_def_data.fees);
 
     assert!(
         pool_def_data.liquidity_pool_supply >= MINIMUM_LIQUIDITY,
diff --git a/amm/src/tests.rs b/amm/src/tests.rs
index f925047..c845815 100644
--- a/amm/src/tests.rs
+++ b/amm/src/tests.rs
@@ -2983,6 +2983,21 @@ fn test_sync_reserves_rejects_pool_below_minimum_liquidity() {
     );
 }
 
+#[should_panic(expected = "Fee tier must be one of 1, 5, 30, or 100 basis points")]
+#[test]
+fn test_sync_reserves_rejects_unsupported_fee_tier() {
+    let mut pool = AccountWithMetadataForTests::pool_definition_init();
+    let mut pool_def = PoolDefinition::try_from(&pool.account.data).unwrap();
+    pool_def.fees = 2;
+    pool.account.data = Data::from(&pool_def);
+
+    let _ = sync_reserves(
+        pool,
+        AccountWithMetadataForTests::vault_a_init(),
+        AccountWithMetadataForTests::vault_b_init(),
+    );
+}
+
 #[test]
 fn test_donation_then_add_liquidity_sync_mitigates_mispricing() {
     let donation_a = 100u128;