diff --git a/stack-orchestrator/container-build/cerc-fixturenet-eth-lighthouse/genesis/cl/build_cl.sh b/stack-orchestrator/container-build/cerc-fixturenet-eth-lighthouse/genesis/cl/build_cl.sh
index 5157b38..1130cb7 100755
--- a/stack-orchestrator/container-build/cerc-fixturenet-eth-lighthouse/genesis/cl/build_cl.sh
+++ b/stack-orchestrator/container-build/cerc-fixturenet-eth-lighthouse/genesis/cl/build_cl.sh
@@ -44,6 +44,11 @@ lcli \
   --interop-genesis-state \
   --force
 
+# Patch the spec with settings not supported by lcli
+sed -i "/^SHARD_COMMITTEE_PERIOD:/s/:.*/: $SHARD_COMMITTEE_PERIOD/" $TESTNET_DIR/config.yaml
+sed -i "/^MIN_VALIDATOR_WITHDRAWABILITY_DELAY:/s/:.*/: $MIN_VALIDATOR_WITHDRAWABILITY_DELAY/" $TESTNET_DIR/config.yaml
+sed -i "/^MAX_SEED_LOOKAHEAD:/s/:.*/: $MAX_SEED_LOOKAHEAD/" $TESTNET_DIR/config.yaml
+
 echo Specification and genesis.ssz generated at $TESTNET_DIR.
 echo "Generating $VALIDATOR_COUNT validators concurrently... (this may take a while)"
 
diff --git a/stack-orchestrator/container-build/cerc-fixturenet-eth-lighthouse/genesis/cl/vars.env b/stack-orchestrator/container-build/cerc-fixturenet-eth-lighthouse/genesis/cl/vars.env
index 54634fc..f790e4c 100644
--- a/stack-orchestrator/container-build/cerc-fixturenet-eth-lighthouse/genesis/cl/vars.env
+++ b/stack-orchestrator/container-build/cerc-fixturenet-eth-lighthouse/genesis/cl/vars.env
@@ -38,6 +38,13 @@ SECONDS_PER_SLOT=${SECONDS_PER_SLOT:-3}
 # Seconds per Eth1 block
 SECONDS_PER_ETH1_BLOCK=${SECONDS_PER_ETH1_BLOCK:-1}
 
+# Min epochs between validator activation and exit
+SHARD_COMMITTEE_PERIOD=2
+# Min epochs between validator exit and withdrawal
+MIN_VALIDATOR_WITHDRAWABILITY_DELAY=1
+# Delay for validator activation/exit
+MAX_SEED_LOOKAHEAD=1
+
 # Command line arguments for validator client
 VC_ARGS=${VC_ARGS:-""}