diff --git a/beacon_node/beacon_chain/src/initialise.rs b/beacon_node/beacon_chain/src/initialise.rs
index 7d3c87965f..58b3aee84c 100644
--- a/beacon_node/beacon_chain/src/initialise.rs
+++ b/beacon_node/beacon_chain/src/initialise.rs
@@ -35,8 +35,12 @@ pub fn initialise_beacon_chain(
     genesis_block.state_root = Hash256::from_slice(&genesis_state.hash_tree_root());
 
     // Slot clock
-    let slot_clock = SystemTimeSlotClock::new(genesis_state.genesis_time, spec.seconds_per_slot)
-        .expect("Unable to load SystemTimeSlotClock");
+    let slot_clock = SystemTimeSlotClock::new(
+        spec.genesis_slot,
+        genesis_state.genesis_time,
+        spec.seconds_per_slot,
+    )
+    .expect("Unable to load SystemTimeSlotClock");
     // Choose the fork choice
     let fork_choice = BitwiseLMDGhost::new(block_store.clone(), state_store.clone());
 
@@ -72,8 +76,12 @@ pub fn initialise_test_beacon_chain(
     genesis_block.state_root = Hash256::from_slice(&genesis_state.hash_tree_root());
 
     // Slot clock
-    let slot_clock = SystemTimeSlotClock::new(genesis_state.genesis_time, spec.seconds_per_slot)
-        .expect("Unable to load SystemTimeSlotClock");
+    let slot_clock = SystemTimeSlotClock::new(
+        spec.genesis_slot,
+        genesis_state.genesis_time,
+        spec.seconds_per_slot,
+    )
+    .expect("Unable to load SystemTimeSlotClock");
     // Choose the fork choice
     let fork_choice = BitwiseLMDGhost::new(block_store.clone(), state_store.clone());
 
diff --git a/beacon_node/rpc/src/beacon_node.rs b/beacon_node/rpc/src/beacon_node.rs
index 54984c5c2a..c92ab66162 100644
--- a/beacon_node/rpc/src/beacon_node.rs
+++ b/beacon_node/rpc/src/beacon_node.rs
@@ -34,6 +34,7 @@ impl BeaconNodeService for BeaconNodeServiceInstance {
 
         node_info.set_fork(fork);
         node_info.set_genesis_time(genesis_time);
+        node_info.set_genesis_slot(self.chain.get_spec().genesis_slot.as_u64());
         node_info.set_chain_id(self.chain.get_spec().chain_id as u32);
 
         // send the node_info the requester
diff --git a/eth2/utils/slot_clock/src/system_time_slot_clock.rs b/eth2/utils/slot_clock/src/system_time_slot_clock.rs
index 99f051985f..816180d6e6 100644
--- a/eth2/utils/slot_clock/src/system_time_slot_clock.rs
+++ b/eth2/utils/slot_clock/src/system_time_slot_clock.rs
@@ -13,6 +13,7 @@ pub enum Error {
 /// Determines the present slot based upon the present system time.
 #[derive(Clone)]
 pub struct SystemTimeSlotClock {
+    genesis_slot: Slot,
     genesis_seconds: u64,
     slot_duration_seconds: u64,
 }
@@ -22,6 +23,7 @@ impl SystemTimeSlotClock {
     ///
     /// Returns an Error if `slot_duration_seconds == 0`.
     pub fn new(
+        genesis_slot: Slot,
         genesis_seconds: u64,
         slot_duration_seconds: u64,
     ) -> Result<SystemTimeSlotClock, Error> {
@@ -29,6 +31,7 @@ impl SystemTimeSlotClock {
             Err(Error::SlotDurationIsZero)
         } else {
             Ok(Self {
+                genesis_slot,
                 genesis_seconds,
                 slot_duration_seconds,
             })
@@ -44,9 +47,11 @@ impl SlotClock for SystemTimeSlotClock {
         let duration_since_epoch = syslot_time.duration_since(SystemTime::UNIX_EPOCH)?;
         let duration_since_genesis =
             duration_since_epoch.checked_sub(Duration::from_secs(self.genesis_seconds));
+
         match duration_since_genesis {
             None => Ok(None),
-            Some(d) => Ok(slot_from_duration(self.slot_duration_seconds, d)),
+            Some(d) => Ok(slot_from_duration(self.slot_duration_seconds, d)
+                .and_then(|s| Some(s + self.genesis_slot))),
         }
     }
 }
@@ -74,6 +79,7 @@ mod tests {
     #[test]
     fn test_slot_now() {
         let slot_time = 100;
+        let genesis_slot = Slot::new(0);
 
         let now = SystemTime::now();
         let since_epoch = now.duration_since(SystemTime::UNIX_EPOCH).unwrap();
@@ -81,18 +87,21 @@ mod tests {
         let genesis = since_epoch.as_secs() - slot_time * 89;
 
         let clock = SystemTimeSlotClock {
+            genesis_slot,
             genesis_seconds: genesis,
             slot_duration_seconds: slot_time,
         };
         assert_eq!(clock.present_slot().unwrap(), Some(Slot::new(89)));
 
         let clock = SystemTimeSlotClock {
+            genesis_slot,
             genesis_seconds: since_epoch.as_secs(),
             slot_duration_seconds: slot_time,
         };
         assert_eq!(clock.present_slot().unwrap(), Some(Slot::new(0)));
 
         let clock = SystemTimeSlotClock {
+            genesis_slot,
             genesis_seconds: since_epoch.as_secs() - slot_time * 42 - 5,
             slot_duration_seconds: slot_time,
         };
diff --git a/protos/src/services.proto b/protos/src/services.proto
index ee4f58d1b0..6b2afceebb 100644
--- a/protos/src/services.proto
+++ b/protos/src/services.proto
@@ -45,6 +45,7 @@ message NodeInfoResponse {
     Fork fork = 2;
     uint32 chain_id = 3;
     uint64 genesis_time = 4;
+    uint64 genesis_slot = 5;
 }
 
 message Fork {
diff --git a/validator_client/src/service.rs b/validator_client/src/service.rs
index 8a7e90d104..eb0771049b 100644
--- a/validator_client/src/service.rs
+++ b/validator_client/src/service.rs
@@ -101,6 +101,7 @@ impl Service {
 
         // build requisite objects to form Self
         let genesis_time = node_info.get_genesis_time();
+        let genesis_slot = Slot::from(node_info.get_genesis_slot());
 
         info!(log,"Beacon node connected"; "Node Version" => node_info.version.clone(), "Chain ID" => node_info.chain_id, "Genesis time" => genesis_time);
 
@@ -117,8 +118,9 @@ impl Service {
 
         // build the validator slot clock
         let slot_clock = {
-            let clock = SystemTimeSlotClock::new(genesis_time, config.spec.seconds_per_slot)
-                .expect("Unable to instantiate SystemTimeSlotClock.");
+            let clock =
+                SystemTimeSlotClock::new(genesis_slot, genesis_time, config.spec.seconds_per_slot)
+                    .expect("Unable to instantiate SystemTimeSlotClock.");
             Arc::new(clock)
         };