diff --git a/beacon_node/beacon_chain/src/beacon_chain.rs b/beacon_node/beacon_chain/src/beacon_chain.rs
index 67e4646c6f..fb2f8ea6a9 100644
--- a/beacon_node/beacon_chain/src/beacon_chain.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain.rs
@@ -151,7 +151,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         let slot_clock = T::SlotClock::from_eth2_genesis(
             spec.genesis_slot,
             genesis_state.genesis_time,
-            Duration::from_secs(spec.seconds_per_slot),
+            Duration::from_millis(spec.milliseconds_per_slot),
         )
         .ok_or_else(|| Error::SlotClockDidNotStart)?;
 
@@ -184,7 +184,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         let slot_clock = T::SlotClock::from_eth2_genesis(
             spec.genesis_slot,
             p.state.genesis_time,
-            Duration::from_secs(spec.seconds_per_slot),
+            Duration::from_millis(spec.milliseconds_per_slot),
         )
         .ok_or_else(|| Error::SlotClockDidNotStart)?;
 
@@ -397,17 +397,6 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         }
     }
 
-    /*
-    /// Returns slot of the present state.
-    ///
-    /// This is distinct to `read_slot_clock`, which reads from the actual system clock. If
-    /// `self.state` has not been transitioned it is possible for the system clock to be on a
-    /// different slot to what is returned from this call.
-    pub fn present_slot(&self) -> Slot {
-        self.state.read().slot
-    }
-    */
-
     /// Returns the block proposer for a given slot.
     ///
     /// Information is read from the present `beacon_state` shuffling, only information from the
diff --git a/beacon_node/client/src/lib.rs b/beacon_node/client/src/lib.rs
index 004353d38b..67528e2f96 100644
--- a/beacon_node/client/src/lib.rs
+++ b/beacon_node/client/src/lib.rs
@@ -76,7 +76,7 @@ where
         executor: &TaskExecutor,
     ) -> error::Result<Self> {
         let store = Arc::new(store);
-        let seconds_per_slot = eth2_config.spec.seconds_per_slot;
+        let milliseconds_per_slot = eth2_config.spec.milliseconds_per_slot;
 
         let spec = &eth2_config.spec.clone();
 
@@ -182,7 +182,7 @@ where
             // set up the validator work interval - start at next slot and proceed every slot
             let interval = {
                 // Set the interval to start at the next slot, and every slot after
-                let slot_duration = Duration::from_secs(seconds_per_slot);
+                let slot_duration = Duration::from_millis(milliseconds_per_slot);
                 //TODO: Handle checked add correctly
                 Interval::new(Instant::now() + duration_to_next_slot, slot_duration)
             };
diff --git a/eth2/types/src/chain_spec.rs b/eth2/types/src/chain_spec.rs
index 9dec626d44..d59e0db0ac 100644
--- a/eth2/types/src/chain_spec.rs
+++ b/eth2/types/src/chain_spec.rs
@@ -58,7 +58,7 @@ pub struct ChainSpec {
     /*
      * Time parameters
      */
-    pub seconds_per_slot: u64,
+    pub milliseconds_per_slot: u64,
     pub min_attestation_inclusion_delay: u64,
     pub min_seed_lookahead: Epoch,
     pub activation_exit_delay: u64,
@@ -158,7 +158,7 @@ impl ChainSpec {
             /*
              * Time parameters
              */
-            seconds_per_slot: 6,
+            milliseconds_per_slot: 6_000,
             min_attestation_inclusion_delay: 1,
             min_seed_lookahead: Epoch::new(1),
             activation_exit_delay: 4,
@@ -221,7 +221,7 @@ impl ChainSpec {
         let boot_nodes = vec![];
 
         Self {
-            seconds_per_slot: 12,
+            milliseconds_per_slot: 12_000,
             target_committee_size: 4,
             shuffle_round_count: 10,
             network_id: 13,
diff --git a/validator_client/src/service.rs b/validator_client/src/service.rs
index 68a9132656..bd694668bf 100644
--- a/validator_client/src/service.rs
+++ b/validator_client/src/service.rs
@@ -161,7 +161,7 @@ impl<B: BeaconNodeDuties + 'static, S: Signer + 'static, E: EthSpec> Service<B,
         let slot_clock = SystemTimeSlotClock::from_eth2_genesis(
             genesis_slot,
             genesis_time,
-            Duration::from_secs(eth2_config.spec.seconds_per_slot),
+            Duration::from_millis(eth2_config.spec.milliseconds_per_slot),
         )
         .ok_or_else::<error_chain::Error, _>(|| {
             "Unable to start slot clock. Genesis may not have occurred yet. Exiting.".into()
@@ -250,7 +250,7 @@ impl<B: BeaconNodeDuties + 'static, S: Signer + 'static, E: EthSpec> Service<B,
         // set up the validator work interval - start at next slot and proceed every slot
         let interval = {
             // Set the interval to start at the next slot, and every slot after
-            let slot_duration = Duration::from_secs(service.spec.seconds_per_slot);
+            let slot_duration = Duration::from_millis(service.spec.milliseconds_per_slot);
             //TODO: Handle checked add correctly
             Interval::new(Instant::now() + duration_to_next_slot, slot_duration)
         };