diff --git a/clients/nimbus-el/mapper.jq b/clients/nimbus-el/mapper.jq
index c674505fb2..37b6e126d7 100644
--- a/clients/nimbus-el/mapper.jq
+++ b/clients/nimbus-el/mapper.jq
@@ -69,6 +69,7 @@ def to_bool:
     "muirGlacierBlock": env.HIVE_FORK_MUIR_GLACIER|to_int,
     "berlinBlock": env.HIVE_FORK_BERLIN|to_int,
     "londonBlock": env.HIVE_FORK_LONDON|to_int,
+    "mergeForkBlock": env.HIVE_MERGE_BLOCK_ID|to_int,
     "terminalTotalDifficulty": env.HIVE_TERMINAL_TOTAL_DIFFICULTY|to_int,
   }|remove_empty
 }
diff --git a/clients/nimbus-el/nimbus.sh b/clients/nimbus-el/nimbus.sh
index bfbee3418f..096d055b7a 100644
--- a/clients/nimbus-el/nimbus.sh
+++ b/clients/nimbus-el/nimbus.sh
@@ -108,7 +108,11 @@ if [ "$HIVE_GRAPHQL_ENABLED" != "" ]; then
 else
   FLAGS="$FLAGS --rpc --rpc-api:eth,debug --rpc-address:0.0.0.0 --rpc-port:8545"
   FLAGS="$FLAGS --ws --ws-api:eth,debug --ws-address:0.0.0.0 --ws-port:8546"
-  FLAGS="$FLAGS --engine-api:true --engine-api-address:0.0.0.0 --engine-api-port:8551"
+fi
+
+if [ "$HIVE_TERMINAL_TOTAL_DIFFICULTY" != "" ]; then
+  echo "0x7365637265747365637265747365637265747365637265747365637265747365" > /jwtsecret
+  FLAGS="$FLAGS --engine-api:true --engine-api-address:0.0.0.0 --engine-api-port:8551 --jwt-secret:/jwtsecret"
 fi
 
 echo "Running nimbus with flags $FLAGS"