diff --git a/implementation/contracts/system/TBTCSystem.sol b/implementation/contracts/system/TBTCSystem.sol
index 9278a128f..1eb3d29b3 100644
--- a/implementation/contracts/system/TBTCSystem.sol
+++ b/implementation/contracts/system/TBTCSystem.sol
@@ -98,8 +98,14 @@ contract TBTCSystem is Ownable, ITBTCSystem, DepositLog {
     /// @dev    Lot sizes should be 
     /// @param _lotSizes Array of allowed lot sizes.
     function setLotSizes(uint256[] calldata _lotSizes) external onlyOwner {
-        lotSizesSatoshis = _lotSizes;
-        emit LotSizesUpdated(_lotSizes);
+        for( uint i = 0; i < _lotSizes.length; i++){
+            if (_lotSizes[i] == 10**8){
+                lotSizesSatoshis = _lotSizes;
+                emit LotSizesUpdated(_lotSizes);
+                return;
+            }
+        }
+        revert("Lot size array must always contain 1BTC");
     }
 
     /// @notice Gets the allowed lot sizes
diff --git a/implementation/test/TBTCSystemTest.js b/implementation/test/TBTCSystemTest.js
index 68e695618..5adac8f38 100644
--- a/implementation/test/TBTCSystemTest.js
+++ b/implementation/test/TBTCSystemTest.js
@@ -89,6 +89,34 @@ contract('TBTCSystem', (accounts) => {
     })
   })
 
+  describe('setLotSizes', async () => {
+    it('sets a different lot size array', async () => {
+      const blockNumber = await web3.eth.getBlock('latest').number
+      const lotSizes = [10**8, 10**6]
+      await tbtcSystem.setLotSizes(lotSizes)
+
+      const eventList = await tbtcSystem.getPastEvents('LotSizesUpdated', { fromBlock: blockNumber, toBlock: 'latest' })
+      assert.equal(eventList.length, 1)
+      expect(eventList[0].returnValues._lotSizes).to.eql(['100000000', '1000000']) // deep equality check
+    })
+
+    it('reverts if lot size array is empty', async () => {
+      const lotSizes = []
+      await expectThrow(
+        tbtcSystem.setLotSizes(lotSizes),
+        'Lot size array must always contain 1BTC'
+      )
+    })
+
+    it('reverts if lot size array does not contain a 1BTC lot size', async () => {
+      const lotSizes = [10**7]
+      await expectThrow(
+        tbtcSystem.setLotSizes(lotSizes),
+        'Lot size array must always contain 1BTC'
+      )
+    })
+  })
+
   describe('emergencyPauseNewDeposits', async () => {
     let term