diff --git a/beacon_chain/validator_induction/src/inductor.rs b/beacon_chain/validator_induction/src/inductor.rs
index c86fce9e6..d26e71bc3 100644
--- a/beacon_chain/validator_induction/src/inductor.rs
+++ b/beacon_chain/validator_induction/src/inductor.rs
@@ -19,7 +19,7 @@ pub enum ValidatorInductionError {
 }
 
 impl ValidatorInductor {
-    pub fn new(current_slot: u64, shard_count: u16, validators: Vec<ValidatorRecord>) -> Self {
+    pub fn new(current_slot: u64, shard_count: u64, validators: Vec<ValidatorRecord>) -> Self {
         Self {
             current_slot,
             shard_count,
diff --git a/beacon_chain/validator_shuffling/Cargo.toml b/beacon_chain/validator_shuffling/Cargo.toml
index 269b5c557..b6c35ec3f 100644
--- a/beacon_chain/validator_shuffling/Cargo.toml
+++ b/beacon_chain/validator_shuffling/Cargo.toml
@@ -6,5 +6,6 @@ authors = ["Paul Hauner <paul@paulhauner.com>"]
 [dependencies]
 active-validators = { path = "../utils/active-validators" }
 honey-badger-split = { path = "../utils/honey-badger-split" }
+spec = { path = "../spec" }
 types = { path = "../types" }
 vec_shuffle = { path = "../utils/vec_shuffle" }
diff --git a/beacon_chain/validator_shuffling/src/lib.rs b/beacon_chain/validator_shuffling/src/lib.rs
index fe2447fc0..61cc02bf1 100644
--- a/beacon_chain/validator_shuffling/src/lib.rs
+++ b/beacon_chain/validator_shuffling/src/lib.rs
@@ -1,5 +1,6 @@
 extern crate active_validators;
 extern crate honey_badger_split;
+extern crate spec;
 extern crate types;
 extern crate vec_shuffle;
 
diff --git a/beacon_chain/validator_shuffling/src/shuffle.rs b/beacon_chain/validator_shuffling/src/shuffle.rs
index 3009f4cbd..3b3009e5d 100644
--- a/beacon_chain/validator_shuffling/src/shuffle.rs
+++ b/beacon_chain/validator_shuffling/src/shuffle.rs
@@ -2,7 +2,8 @@ use std::cmp::min;
 
 use active_validators::active_validator_indices;
 use honey_badger_split::SplitExt;
-use types::{ChainConfig, ShardAndCommittee, ValidatorRecord};
+use spec::ChainSpec;
+use types::{ShardAndCommittee, ValidatorRecord};
 use vec_shuffle::{shuffle, ShuffleErr};
 
 type DelegatedCycle = Vec<Vec<ShardAndCommittee>>;
@@ -21,21 +22,21 @@ pub fn shard_and_committees_for_cycle(
     seed: &[u8],
     validators: &[ValidatorRecord],
     crosslinking_shard_start: u16,
-    config: &ChainConfig,
+    spec: &ChainSpec,
 ) -> Result<DelegatedCycle, ValidatorAssignmentError> {
     let shuffled_validator_indices = {
         let mut validator_indices = active_validator_indices(validators);
         shuffle(seed, validator_indices)?
     };
-    let shard_indices: Vec<usize> = (0_usize..config.shard_count as usize).into_iter().collect();
+    let shard_indices: Vec<usize> = (0_usize..spec.shard_count as usize).into_iter().collect();
     let crosslinking_shard_start = crosslinking_shard_start as usize;
-    let cycle_length = config.cycle_length as usize;
-    let min_committee_size = config.min_committee_size as usize;
+    let epoch_length = spec.epoch_length as usize;
+    let min_committee_size = spec.target_committee_size as usize;
     generate_cycle(
         &shuffled_validator_indices,
         &shard_indices,
         crosslinking_shard_start,
-        cycle_length,
+        epoch_length,
         min_committee_size,
     )
 }
@@ -45,29 +46,29 @@ fn generate_cycle(
     validator_indices: &[usize],
     shard_indices: &[usize],
     crosslinking_shard_start: usize,
-    cycle_length: usize,
+    epoch_length: usize,
     min_committee_size: usize,
 ) -> Result<DelegatedCycle, ValidatorAssignmentError> {
     let validator_count = validator_indices.len();
     let shard_count = shard_indices.len();
 
-    if shard_count / cycle_length == 0 {
+    if shard_count / epoch_length == 0 {
         return Err(ValidatorAssignmentError::TooFewShards);
     }
 
     let (committees_per_slot, slots_per_committee) = {
-        if validator_count >= cycle_length * min_committee_size {
+        if validator_count >= epoch_length * min_committee_size {
             let committees_per_slot = min(
-                validator_count / cycle_length / (min_committee_size * 2) + 1,
-                shard_count / cycle_length,
+                validator_count / epoch_length / (min_committee_size * 2) + 1,
+                shard_count / epoch_length,
             );
             let slots_per_committee = 1;
             (committees_per_slot, slots_per_committee)
         } else {
             let committees_per_slot = 1;
             let mut slots_per_committee = 1;
-            while (validator_count * slots_per_committee < cycle_length * min_committee_size)
-                & (slots_per_committee < cycle_length)
+            while (validator_count * slots_per_committee < epoch_length * min_committee_size)
+                & (slots_per_committee < epoch_length)
             {
                 slots_per_committee *= 2;
             }
@@ -76,7 +77,7 @@ fn generate_cycle(
     };
 
     let cycle = validator_indices
-        .honey_badger_split(cycle_length)
+        .honey_badger_split(epoch_length)
         .enumerate()
         .map(|(i, slot_indices)| {
             let shard_start =
@@ -108,7 +109,7 @@ mod tests {
         validator_count: &usize,
         shard_count: &usize,
         crosslinking_shard_start: usize,
-        cycle_length: usize,
+        epoch_length: usize,
         min_committee_size: usize,
     ) -> (
         Vec<usize>,
@@ -121,7 +122,7 @@ mod tests {
             &validator_indices,
             &shard_indices,
             crosslinking_shard_start,
-            cycle_length,
+            epoch_length,
             min_committee_size,
         );
         (validator_indices, shard_indices, result)
@@ -183,13 +184,13 @@ mod tests {
         let validator_count: usize = 100;
         let shard_count: usize = 20;
         let crosslinking_shard_start: usize = 0;
-        let cycle_length: usize = 20;
+        let epoch_length: usize = 20;
         let min_committee_size: usize = 10;
         let (validators, shards, result) = generate_cycle_helper(
             &validator_count,
             &shard_count,
             crosslinking_shard_start,
-            cycle_length,
+            epoch_length,
             min_committee_size,
         );
         let cycle = result.unwrap();
@@ -242,13 +243,13 @@ mod tests {
         let validator_count: usize = 523;
         let shard_count: usize = 31;
         let crosslinking_shard_start: usize = 0;
-        let cycle_length: usize = 11;
+        let epoch_length: usize = 11;
         let min_committee_size: usize = 5;
         let (validators, shards, result) = generate_cycle_helper(
             &validator_count,
             &shard_count,
             crosslinking_shard_start,
-            cycle_length,
+            epoch_length,
             min_committee_size,
         );
         let cycle = result.unwrap();