diff --git a/crates/ethcore/src/engines/unity/mod.rs b/crates/ethcore/src/engines/unity/mod.rs
index ce3acc89ce..b4baacec55 100644
--- a/crates/ethcore/src/engines/unity/mod.rs
+++ b/crates/ethcore/src/engines/unity/mod.rs
@@ -753,7 +753,7 @@ impl Unity {
         machine: EthereumMachine,
         optimize_for: T,
     ) -> Result<Arc<Self>, Error> {
-        debug!("unity params: {:?}, {:?}, {:?}, {:?}, {:?}, {:?}",
+        debug!("unity params: {:?}, {:?}, {:?}, {:?}, {:?}",
                our_params.minimum_difficulty,
                our_params.block_reward,
                our_params.two_thirds_majority_transition,
@@ -2207,7 +2207,6 @@ mod tests {
             durations: [StepDurationInfo {
                 transition_step: 0,
                 transition_timestamp: 0,
-                step_duration: 1,
             }]
             .to_vec()
             .into_iter()
@@ -2368,7 +2367,6 @@ mod tests {
     fn should_collect_block_reward_transitions() {
         let config = r#"{
 			"params": {
-				"stepDuration": "5",
 				"validators": {
 					"list" : ["0x1000000000000000000000000000000000000001"]
 				},
@@ -2419,7 +2417,6 @@ mod tests {
     fn should_reject_out_of_order_block_reward_transition() {
         let config = r#"{
 			"params": {
-				"stepDuration": "5",
 				"validators": {
 					"list" : ["0x1000000000000000000000000000000000000001"]
 				},
diff --git a/crates/ethcore/src/spec/spec.rs b/crates/ethcore/src/spec/spec.rs
index 41d120f18b..8e2c3639c8 100644
--- a/crates/ethcore/src/spec/spec.rs
+++ b/crates/ethcore/src/spec/spec.rs
@@ -727,7 +727,12 @@ impl Spec {
                     .expect("Failed to start AuthorityRound consensus engine.")
             },
             ethjson::spec::Engine::Unity(unity) => {
-                Unity::new(unity.params.into(), machine)
+                Unity::new(
+                    spec_params.cache_dir,
+                    unity.params.into(), 
+                    machine,
+                    spec_params.optimization_setting,
+                    )
                     .expect("Failed to start Unity consensus engine.")
             }
         };
diff --git a/crates/ethjson/src/spec/unity.rs b/crates/ethjson/src/spec/unity.rs
index 1e684f1912..770b4a52a6 100644
--- a/crates/ethjson/src/spec/unity.rs
+++ b/crates/ethjson/src/spec/unity.rs
@@ -23,7 +23,6 @@
 //!
 //! ```ignore
 //! "params": {
-//!     "stepDuration": "5",
 //!     "validators": {
 //!         "multi": {
 //!             "0": {
@@ -113,7 +112,7 @@ mod tests {
     use crate::{
         hash::Address,
         spec::{
-            unity::Unity, step_duration::StepDuration,
+            unity::Unity,
             validator_set::ValidatorSet,
         },
         uint::Uint,
@@ -126,7 +125,6 @@ mod tests {
     fn authority_round_deserialization() {
         let s = r#"{
 			"params": {
-				"stepDuration": "0x02",
 				"validators": {
 					"list" : ["0xc6d9d2cd449a754c494264e1809c50e34d64562b"]
 				},
@@ -146,10 +144,6 @@ mod tests {
 		}"#;
 
         let deserialized: Unity = serde_json::from_str(s).unwrap();
-        assert_eq!(
-            deserialized.params.step_duration,
-            StepDuration::Single(Uint(U256::from(2)))
-        );
         assert_eq!(
             deserialized.params.validators,
             ValidatorSet::List(vec![Address(
@@ -200,7 +194,6 @@ mod tests {
     fn authority_round_deserialization_multi_block() {
         let s = r#"{
 			"params": {
-				"stepDuration": "0x02",
 				"validators": {
 					"contract" : "0xc6d9d2cd449a754c494264e1809c50e34d64562b"
 				},
@@ -212,10 +205,6 @@ mod tests {
 		}"#;
 
         let deserialized: Unity = serde_json::from_str(s).unwrap();
-        assert_eq!(
-            deserialized.params.step_duration,
-            StepDuration::Single(Uint(U256::from(0x02)))
-        );
         assert_eq!(
             deserialized.params.validators,
             ValidatorSet::Contract(Address(