diff --git a/README.md b/README.md
index ef7793f..2487fcd 100644
--- a/README.md
+++ b/README.md
@@ -4,14 +4,15 @@
 
 [Registry.sol](src/Registry.sol)
 - [x] Reduce `MIN_COLLATERAL` to 0.1 ETH. It needs to be non-zero to incentivize people to slash bad registrations.
-- [ ] Rename `proxyKey` to `commitmentKey`.
-- [ ] ~~Optimistically accept an `OperatorCommitment` hash. It can be proven as fraudulent by generating the merkle tree in the fraud proof.~~
-- [ ] Make the unregistration delay parameterizable by the proposer but requires it to be at least `TWO_EPOCHS`.
+- [X] Rename `proxyKey` to `commitmentKey`.
+- [X] ~~Optimistically accept an `OperatorCommitment` hash. It can be proven as fraudulent by generating the merkle tree in the fraud proof.~~
+- [X] Make the unregistration delay parameterizable by the proposer but requires it to be at least `TWO_EPOCHS`.
 - [ ] Spec out the `Registration` message signed by a Validator BLS key. 
 - [ ] Make sure no one can overwrite an `OperatorCommitment`
 - [ ] Save the `Operator.collateral` as GWEI.
 - [ ] Diagram the registration process
-- [ ] Add field to `Operator` struct to signal if they are a gateway (open for discussion). 
+- [ ] Add field to `Operator` struct to signal if they are a gateway (open for discussion).
+
 
 
 [BytecodeSlasher.sol](src/BytecodeSlasher.sol)
@@ -55,4 +56,5 @@ struct RegistrationMessage {
     // Arbitrary metadata to be included in the delegation (we should include the OperatorCommitment)
     bytes metadata; 
 }
-```
\ No newline at end of file
+```
+
diff --git a/src/Registry.sol b/src/Registry.sol
index 47f638e..e00c72c 100644
--- a/src/Registry.sol
+++ b/src/Registry.sol
@@ -18,6 +18,7 @@ contract Registry {
         uint72 collateral; // todo save as GWEI
         uint32 registeredAt;
         uint32 unregisteredAt;
+        uint32 unregistrationDelay;
         // anything else?
     }
 
@@ -30,7 +31,7 @@ contract Registry {
 
     // Constants
     uint256 constant MIN_COLLATERAL = 0.1 ether;
-    uint256 constant TWO_EPOCHS = 64; // parameterize when you join
+    uint256 constant TWO_EPOCHS = 64;
 
     // Errors
     error InsufficientCollateral();
@@ -41,6 +42,8 @@ contract Registry {
     error NoCollateralToClaim();
     error FraudProofMerklePathInvalid();
     error FraudProofChallengeInvalid();
+    error UnregistrationDelayTooShort();
+
     // Events
     event OperatorRegistered(bytes32 operatorCommitment, uint32 registeredAt);
     event OperatorUnregistered(
@@ -52,6 +55,7 @@ contract Registry {
     function register(
         Registration[] calldata registrations,
         bytes32 commitmentKey,
+        uint32 unregistrationDelay,
         uint256 height
     ) external payable {
         // check collateral
@@ -59,6 +63,10 @@ contract Registry {
             revert InsufficientCollateral();
         }
 
+        if (unregistrationDelay < TWO_EPOCHS) {
+            revert UnregistrationDelayTooShort();
+        }
+
         // operatorCommitment hash = merklize registrations
         bytes32 operatorCommitment = createCommitment(
             registrations,
@@ -72,6 +80,7 @@ contract Registry {
             commitmentKey: commitmentKey,
             collateral: uint72(msg.value), // todo save as GWEI
             registeredAt: uint32(block.number),
+            unregistrationDelay: unregistrationDelay,
             unregisteredAt: 0
         });
 
@@ -181,7 +190,7 @@ contract Registry {
         }
 
         // Check that enough time has passed
-        if (block.number < operator.unregisteredAt + TWO_EPOCHS) {
+        if (block.number < operator.unregisteredAt + operator.unregistrationDelay) {
             revert UnregistrationDelayNotMet();
         }