diff --git a/crates/optimism/evm/src/config.rs b/crates/optimism/evm/src/config.rs
index b32b0929424d..e595b653ed18 100644
--- a/crates/optimism/evm/src/config.rs
+++ b/crates/optimism/evm/src/config.rs
@@ -12,10 +12,10 @@ pub fn revm_spec_by_timestamp_after_bedrock(
     chain_spec: &OpChainSpec,
     timestamp: u64,
 ) -> revm_primitives::SpecId {
-    if chain_spec.fork(OpHardfork::Isthmus).active_at_timestamp(timestamp) {
-        todo!()
-    } else if chain_spec.fork(OpHardfork::Holocene).active_at_timestamp(timestamp) {
-        revm_primitives::HOLOCENE
+    if chain_spec.fork(OpHardfork::Isthmus).active_at_timestamp(timestamp) ||
+        chain_spec.fork(OpHardfork::Holocene).active_at_timestamp(timestamp)
+    {
+        revm_primitives::HOLOCENE // todo: replace <https://github.com/bluealloy/revm/issues/1874>
     } else if chain_spec.fork(OpHardfork::Granite).active_at_timestamp(timestamp) {
         revm_primitives::GRANITE
     } else if chain_spec.fork(OpHardfork::Fjord).active_at_timestamp(timestamp) {
@@ -33,10 +33,10 @@ pub fn revm_spec_by_timestamp_after_bedrock(
 
 /// Map the latest active hardfork at the given block to a revm [`SpecId`](revm_primitives::SpecId).
 pub fn revm_spec(chain_spec: &OpChainSpec, block: &Head) -> revm_primitives::SpecId {
-    if chain_spec.fork(OpHardfork::Isthmus).active_at_head(block) {
-        todo!()
-    } else if chain_spec.fork(OpHardfork::Holocene).active_at_head(block) {
-        revm_primitives::HOLOCENE
+    if chain_spec.fork(OpHardfork::Isthmus).active_at_head(block) ||
+        chain_spec.fork(OpHardfork::Holocene).active_at_head(block)
+    {
+        revm_primitives::HOLOCENE // todo: replace <https://github.com/bluealloy/revm/issues/1874>
     } else if chain_spec.fork(OpHardfork::Granite).active_at_head(block) {
         revm_primitives::GRANITE
     } else if chain_spec.fork(OpHardfork::Fjord).active_at_head(block) {