diff --git a/evm/src/cpu/kernel/asm/core/gas.asm b/evm/src/cpu/kernel/asm/core/gas.asm
index ad2966a5..436ccb3e 100644
--- a/evm/src/cpu/kernel/asm/core/gas.asm
+++ b/evm/src/cpu/kernel/asm/core/gas.asm
@@ -15,8 +15,36 @@ global sys_gas:
     %mload_context_metadata(@CTX_METADATA_GAS_LIMIT)
 %endmacro
 
-// Charge gas. Faults if we exceed the limit for the current context.
+
+// TODO: `%refund_gas` and `refund_gas_hook` are hooks used for debugging. They should be removed at some point and `refund_gas_original` renamed to `refund_gas`.
+%macro refund_gas
+    PUSH %%after %jump(refund_gas_hook)
+%%after:
+    %refund_gas_original
+%endmacro
+
+global refund_gas_hook:
+    JUMP
+
+%macro refund_gas_original
+    // stack: amount
+    %mload_global_metadata(@GLOBAL_METADATA_REFUND_COUNTER)
+    ADD
+    %mstore_global_metadata(@GLOBAL_METADATA_REFUND_COUNTER)
+%endmacro
+
+// TODO: `%charge_gas` and `charge_gas_hook` are hooks used for debugging. They should be removed at some point and `charge_gas_original` renamed to `charge_gas`.
 %macro charge_gas
+    PUSH %%after %jump(charge_gas_hook)
+%%after:
+    %charge_gas_original
+%endmacro
+
+global charge_gas_hook:
+    JUMP
+
+// Charge gas. Faults if we exceed the limit for the current context.
+%macro charge_gas_original
     // stack: gas, kexit_info
     %shl_const(192)
     ADD
diff --git a/evm/src/cpu/kernel/asm/core/process_txn.asm b/evm/src/cpu/kernel/asm/core/process_txn.asm
index a7ccf864..97d9b8c5 100644
--- a/evm/src/cpu/kernel/asm/core/process_txn.asm
+++ b/evm/src/cpu/kernel/asm/core/process_txn.asm
@@ -278,7 +278,7 @@ global process_message_txn_after_call:
     // stack: used_gas, leftover_gas
     %mload_global_metadata(@GLOBAL_METADATA_REFUND_COUNTER)
     // stack: refund, used_gas, leftover_gas
-    DUP2 %div_const(2) // max_refund = used_gas/2
+    DUP2 %div_const(@MAX_REFUND_QUOTIENT) // max_refund = used_gas/5
     // stack: max_refund, refund, used_gas, leftover_gas
     %min
     %stack (refund, used_gas, leftover_gas) -> (leftover_gas, refund, refund, used_gas)
diff --git a/evm/src/cpu/kernel/asm/mpt/storage/storage_write.asm b/evm/src/cpu/kernel/asm/mpt/storage/storage_write.asm
index af8bc912..6383b871 100644
--- a/evm/src/cpu/kernel/asm/mpt/storage/storage_write.asm
+++ b/evm/src/cpu/kernel/asm/mpt/storage/storage_write.asm
@@ -35,9 +35,54 @@ sstore_warm:
     %add_const(@GAS_WARMACCESS)
 
 sstore_charge_gas:
-    %stack (gas, original_value, current_value, kexit_info, slot, value) -> (gas, kexit_info, current_value, slot, value)
+    %stack (gas, original_value, current_value, kexit_info, slot, value) -> (gas, kexit_info, current_value, value, original_value, slot)
     %charge_gas
 
+sstore_refund:
+    %stack (kexit_info, current_value, value, original_value, slot) -> (current_value, value, current_value, value, original_value, slot, kexit_info)
+    EQ %jumpi(sstore_no_refund)
+    %stack (current_value, value, original_value, slot, kexit_info) -> (current_value, original_value, current_value, value, original_value, slot, kexit_info)
+    EQ %jumpi(sstore_refund_original)
+    %stack (current_value, value, original_value, slot, kexit_info) -> (original_value, current_value, value, original_value, slot, kexit_info)
+    ISZERO %jumpi(sstore_dirty_reset)
+    %stack (current_value, value, original_value, slot, kexit_info) -> (current_value, current_value, value, original_value, slot, kexit_info)
+    ISZERO %jumpi(sstore_dirty_clear1)
+    %stack (current_value, value, original_value, slot, kexit_info) -> (value, current_value, value, original_value, slot, kexit_info)
+    ISZERO %jumpi(sstore_dirty_clear2)
+    %jump(sstore_dirty_reset)
+
+sstore_dirty_clear1:
+    PUSH @REFUND_SCLEAR PUSH 0 SUB %refund_gas
+    %jump(sstore_dirty_reset)
+
+sstore_dirty_clear2:
+    PUSH @REFUND_SCLEAR %refund_gas
+
+sstore_dirty_reset:
+    %stack (current_value, value, original_value, slot, kexit_info) -> (original_value, value, current_value, value, original_value, slot, kexit_info)
+    EQ %jumpi(sstore_dirty_reset2)
+    %jump(sstore_no_refund)
+sstore_dirty_reset2:
+    %stack (current_value, value, original_value, slot, kexit_info) -> (original_value, current_value, value, original_value, slot, kexit_info)
+    ISZERO %jumpi(sstore_dirty_reset_sset)
+    PUSH @GAS_WARMACCESS PUSH @GAS_SRESET SUB %refund_gas
+    %jump(sstore_no_refund)
+sstore_dirty_reset_sset:
+    PUSH @GAS_WARMACCESS PUSH @GAS_SSET SUB %refund_gas
+    %jump(sstore_no_refund)
+
+sstore_refund_original:
+    %stack (current_value, value, original_value, slot, kexit_info) -> (value, current_value, value, original_value, slot, kexit_info)
+    ISZERO %jumpi(sstore_sclear)
+    %jump(sstore_no_refund)
+sstore_sclear:
+    PUSH @REFUND_SCLEAR %refund_gas
+    %jump(sstore_no_refund)
+
+sstore_no_refund:
+    %stack (current_value, value, original_value, slot, kexit_info) -> (kexit_info, current_value, slot, value)
+sstore_after_refund:
+    // stack: kexit_info, current_value, slot, value
     // Check if `value` is equal to `current_value`, and if so exit the kernel early.
     %stack (kexit_info, current_value, slot, value) -> (value, current_value, slot, value, kexit_info)
     EQ %jumpi(sstore_noop)
diff --git a/evm/src/cpu/kernel/constants/mod.rs b/evm/src/cpu/kernel/constants/mod.rs
index b1486589..e8489650 100644
--- a/evm/src/cpu/kernel/constants/mod.rs
+++ b/evm/src/cpu/kernel/constants/mod.rs
@@ -32,6 +32,10 @@ pub fn evm_constants() -> HashMap<String, U256> {
         c.insert(name.into(), U256::from(value));
     }
 
+    for (name, value) in REFUND_CONSTANTS {
+        c.insert(name.into(), U256::from(value));
+    }
+
     for (name, value) in PRECOMPILES {
         c.insert(name.into(), U256::from(value));
     }
@@ -175,7 +179,7 @@ const EC_CONSTANTS: [(&str, [u8; 32]); 20] = [
     ),
 ];
 
-const GAS_CONSTANTS: [(&str, u16); 38] = [
+const GAS_CONSTANTS: [(&str, u16); 36] = [
     ("GAS_ZERO", 0),
     ("GAS_JUMPDEST", 1),
     ("GAS_BASE", 2),
@@ -192,8 +196,6 @@ const GAS_CONSTANTS: [(&str, u16); 38] = [
     ("GAS_COLDSLOAD_MINUS_WARMACCESS", 2_000),
     ("GAS_SSET", 20_000),
     ("GAS_SRESET", 2_900),
-    ("REFUND_SCLEAR", 15_000),
-    ("REFUND_SELFDESTRUCT", 24_000),
     ("GAS_SELFDESTRUCT", 5_000),
     ("GAS_CREATE", 32_000),
     ("GAS_CODEDEPOSIT", 200),
@@ -216,6 +218,8 @@ const GAS_CONSTANTS: [(&str, u16); 38] = [
     ("GAS_BLOCKHASH", 20),
 ];
 
+const REFUND_CONSTANTS: [(&str, u16); 2] = [("REFUND_SCLEAR", 4_800), ("MAX_REFUND_QUOTIENT", 5)];
+
 const PRECOMPILES: [(&str, u16); 9] = [
     ("ECREC", 1),
     ("SHA256", 2),