diff --git a/crates/apollo_starknet_os_program/src/cairo/starkware/starknet/core/os/constants.cairo b/crates/apollo_starknet_os_program/src/cairo/starkware/starknet/core/os/constants.cairo
index c7064150458..15063749ffb 100644
--- a/crates/apollo_starknet_os_program/src/cairo/starkware/starknet/core/os/constants.cairo
+++ b/crates/apollo_starknet_os_program/src/cairo/starkware/starknet/core/os/constants.cairo
@@ -114,7 +114,7 @@ const GET_BLOCK_HASH_GAS_COST = 10810;
 const GET_CLASS_HASH_AT_GAS_COST = 10000;
 const GET_EXECUTION_INFO_GAS_COST = 11240;
 const LIBRARY_CALL_GAS_COST = 88660;
-const REPLACE_CLASS_GAS_COST = 10670;
+const REPLACE_CLASS_GAS_COST = 10000;
 // TODO(Yoni, 1/1/2026): take into account Patricia updates and dict squash.
 const STORAGE_READ_GAS_COST = 24070;
 const STORAGE_WRITE_GAS_COST = 59970;
diff --git a/crates/apollo_starknet_os_program/src/program_hash.json b/crates/apollo_starknet_os_program/src/program_hash.json
index 64f3c8db1af..89b9ea3f334 100644
--- a/crates/apollo_starknet_os_program/src/program_hash.json
+++ b/crates/apollo_starknet_os_program/src/program_hash.json
@@ -1,5 +1,5 @@
 {
-  "os": "0x77bc8c7e1299ba48af772cc93b3adcf80a9234b417ab246f6bba13bf9d7eb62",
+  "os": "0x7295d1b71ceaae707f97f40aea51737858a868080640ff737711904577ae53d",
   "virtual_os": "0x5891e31f2ecaef526289d8606707cde731bc4eae584e9f62ee50847d846cb3d",
   "aggregator": "0x700786d51b3854af43d8e12180380bda3029be6c1767e007858de6ca2edac40",
   "aggregator_with_prefix": "0xe08d300e3f5996e43d6d7cc5a20068e0e58cf1309089f2348317ac580f6c1f"
diff --git a/crates/blockifier/resources/blockifier_versioned_constants_0_14_4.json b/crates/blockifier/resources/blockifier_versioned_constants_0_14_4.json
index baaf4820e06..73081201e43 100644
--- a/crates/blockifier/resources/blockifier_versioned_constants_0_14_4.json
+++ b/crates/blockifier/resources/blockifier_versioned_constants_0_14_4.json
@@ -378,7 +378,7 @@
                 }
             },
             "ReplaceClass": {
-                "n_steps": 106,
+                "n_steps": 92,
                 "n_memory_holes": 0,
                 "builtin_instance_counter": {
                     "range_check_builtin": 1
diff --git a/crates/blockifier/resources/versioned_constants_diff_regression/0.14.3_0.14.4.txt b/crates/blockifier/resources/versioned_constants_diff_regression/0.14.3_0.14.4.txt
index 51fbd8cb91a..c71883d434e 100644
--- a/crates/blockifier/resources/versioned_constants_diff_regression/0.14.3_0.14.4.txt
+++ b/crates/blockifier/resources/versioned_constants_diff_regression/0.14.3_0.14.4.txt
@@ -8,4 +8,5 @@
 ~ /os_resources/execute_syscalls/KeccakRound/n_steps: 316
 ~ /os_resources/execute_syscalls/LibraryCall/n_steps: 874
 ~ /os_resources/execute_syscalls/MetaTxV0/constant/n_steps: 1307
+~ /os_resources/execute_syscalls/ReplaceClass/n_steps: 92
 ~ /os_resources/execute_syscalls/Sha256ProcessBlock/n_steps: 1854
diff --git a/crates/blockifier/src/execution/syscalls/syscall_tests/replace_class.rs b/crates/blockifier/src/execution/syscalls/syscall_tests/replace_class.rs
index d7c592c29ab..40f51f7a7cd 100644
--- a/crates/blockifier/src/execution/syscalls/syscall_tests/replace_class.rs
+++ b/crates/blockifier/src/execution/syscalls/syscall_tests/replace_class.rs
@@ -85,7 +85,7 @@ fn positive_flow(runnable_version: RunnableCairo1) {
             l2_to_l1_messages: [],
             cairo_native: false,
             failed: false,
-            gas_consumed: 14150,
+            gas_consumed: 13480,
         }
     "#]]
     .assert_debug_eq(&execution);
diff --git a/crates/blockifier_test_utils/resources/feature_contracts/cairo1/os_resources_test_contract.cairo b/crates/blockifier_test_utils/resources/feature_contracts/cairo1/os_resources_test_contract.cairo
index 69468d214bb..d77095f1722 100644
--- a/crates/blockifier_test_utils/resources/feature_contracts/cairo1/os_resources_test_contract.cairo
+++ b/crates/blockifier_test_utils/resources/feature_contracts/cairo1/os_resources_test_contract.cairo
@@ -6,7 +6,7 @@ mod OsResourcesTestContract {
     use starknet::info::SyscallResultTrait;
     use starknet::syscalls::{
         call_contract_syscall, deploy_syscall, emit_event_syscall, get_execution_info_v3_syscall,
-        keccak_syscall, library_call_syscall, sha256_process_block_syscall,
+        keccak_syscall, library_call_syscall, replace_class_syscall, sha256_process_block_syscall,
     };
     use starknet::{ClassHash, ContractAddress, get_block_hash_syscall, get_class_hash_at_syscall};
 
@@ -113,5 +113,8 @@ mod OsResourcesTestContract {
         let mut input = BoxTrait::new([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]);
         let mut state = sha256_state_handle_init(BoxTrait::new(SHA256_INITIAL_STATE));
         let _ = sha256_process_block_syscall(state, input).unwrap_syscall();
+
+        // replace class syscall.
+        replace_class_syscall(stable_class_hash).unwrap_syscall();
     }
 }
diff --git a/crates/starknet_os_flow_tests/src/os_resources_test.rs b/crates/starknet_os_flow_tests/src/os_resources_test.rs
index 6bc82299c57..f1dd4329176 100644
--- a/crates/starknet_os_flow_tests/src/os_resources_test.rs
+++ b/crates/starknet_os_flow_tests/src/os_resources_test.rs
@@ -47,7 +47,7 @@ use crate::test_manager::{
 use crate::tests::NON_TRIVIAL_RESOURCE_BOUNDS;
 
 // TODO(Dori): Delete this, or at least reduce it to a minimal set of unmeasurable syscalls.
-const UNMEASURABLE_SYSCALLS: [Selector; 25] = [
+const UNMEASURABLE_SYSCALLS: [Selector; 24] = [
     Selector::DelegateCall,
     Selector::DelegateL1Handler,
     Selector::GetBlockNumber,
@@ -59,7 +59,6 @@ const UNMEASURABLE_SYSCALLS: [Selector; 25] = [
     Selector::GetTxSignature,
     Selector::Sha512ProcessBlock,
     Selector::LibraryCallL1Handler,
-    Selector::ReplaceClass,
     Selector::Secp256k1Add,
     Selector::Secp256k1GetPointFromX,
     Selector::Secp256k1GetXy,