diff --git a/evm/src/cpu/kernel/asm/account_code.asm b/evm/src/cpu/kernel/asm/account_code.asm
index 0353b481..7d560ec1 100644
--- a/evm/src/cpu/kernel/asm/account_code.asm
+++ b/evm/src/cpu/kernel/asm/account_code.asm
@@ -8,6 +8,12 @@
     // stack: codehash
 %endmacro
 
+
+%macro codesize
+    ADDRESS
+    %extcodesize
+%endmacro
+
 %macro extcodesize
     %stack (address) -> (address, %%after)
     %jump(load_code)
@@ -20,10 +26,6 @@ global extcodesize:
     // stack: extcodesize(address), retdest
     SWAP1 JUMP
 
-%macro codesize
-    ADDRESS
-    %extcodesize
-%endmacro
 
 %macro codecopy
     // stack: dest_offset, offset, size, retdest
@@ -73,14 +75,15 @@ extcodecopy_loop:
     %stack (i, code_length, offset, dest_offset, size, retdest) -> (i, size, code_length, offset, dest_offset, retdest)
     %jump(extcodecopy_loop)
 
-
-
-
 extcodecopy_end:
-    %stack (i, size, code_length, offset, dest_offset, size, retdest) -> (retdest)
+    %stack (i, size, code_length, offset, dest_offset, retdest) -> (retdest)
     JUMP
 
 
+// Loads the code at `address` in the `SEGMENT_KERNEL_ACCOUNT_CODE` at the current context and starting at offset 0.
+// Checks that the hash of the loaded code corresponds to the `codehash` in the state trie.
+// Pre stack: address, retdest
+// Post stack: extcodesize(address)
 load_code:
     // stack: address, retdest
     %extcodehash
diff --git a/evm/src/cpu/kernel/interpreter.rs b/evm/src/cpu/kernel/interpreter.rs
index 8057792b..478d5413 100644
--- a/evm/src/cpu/kernel/interpreter.rs
+++ b/evm/src/cpu/kernel/interpreter.rs
@@ -71,7 +71,7 @@ pub struct Interpreter<'a> {
     kernel_mode: bool,
     jumpdests: Vec<usize>,
     pub(crate) offset: usize,
-    context: usize,
+    pub(crate) context: usize,
     pub(crate) memory: InterpreterMemory,
     pub(crate) generation_state: GenerationState<F>,
     prover_inputs_map: &'a HashMap<usize, ProverInputFn>,
diff --git a/evm/src/cpu/kernel/tests/account_code.rs b/evm/src/cpu/kernel/tests/account_code.rs
index 0efd96eb..0576e0e4 100644
--- a/evm/src/cpu/kernel/tests/account_code.rs
+++ b/evm/src/cpu/kernel/tests/account_code.rs
@@ -11,6 +11,7 @@ use crate::cpu::kernel::constants::global_metadata::GlobalMetadata;
 use crate::cpu::kernel::interpreter::Interpreter;
 use crate::cpu::kernel::tests::mpt::nibbles_64;
 use crate::generation::mpt::{all_mpt_prover_inputs_reversed, AccountRlp};
+use crate::memory::segments::Segment;
 
 fn test_account(code: &[u8]) -> AccountRlp {
     AccountRlp {
@@ -23,11 +24,12 @@ fn test_account(code: &[u8]) -> AccountRlp {
 
 fn random_code() -> Vec<u8> {
     let mut rng = thread_rng();
-    let num_bytes = rng.gen_range(0..10000);
+    let num_bytes = rng.gen_range(0..1000);
     (0..num_bytes).map(|_| rng.gen()).collect()
 }
 
 // Stolen from `tests/mpt/insert.rs`
+// Prepare the interpreter by inserting the account in the state trie.
 fn prepare_interpreter(
     interpreter: &mut Interpreter,
     address: Address,
@@ -99,6 +101,33 @@ fn prepare_interpreter(
     Ok(())
 }
 
+#[test]
+fn test_extcodesize() -> Result<()> {
+    let code = random_code();
+    let account = test_account(&code);
+
+    let mut interpreter = Interpreter::new_with_kernel(0, vec![]);
+    let address: Address = thread_rng().gen();
+    // Prepare the interpreter by inserting the account in the state trie.
+    prepare_interpreter(&mut interpreter, address, &account)?;
+
+    let extcodesize = KERNEL.global_labels["extcodesize"];
+
+    // Test `extcodesize`
+    interpreter.offset = extcodesize;
+    interpreter.pop();
+    assert!(interpreter.stack().is_empty());
+    interpreter.push(0xDEADBEEFu32.into());
+    interpreter.push(U256::from_big_endian(address.as_bytes()));
+    interpreter.generation_state.inputs.contract_code =
+        HashMap::from([(keccak(&code), code.clone())]);
+    interpreter.run()?;
+
+    assert_eq!(interpreter.stack(), vec![code.len().into()]);
+
+    Ok(())
+}
+
 #[test]
 fn test_extcodecopy() -> Result<()> {
     let code = random_code();
@@ -106,19 +135,47 @@ fn test_extcodecopy() -> Result<()> {
 
     let mut interpreter = Interpreter::new_with_kernel(0, vec![]);
     let address: Address = thread_rng().gen();
+    // Prepare the interpreter by inserting the account in the state trie.
     prepare_interpreter(&mut interpreter, address, &account)?;
 
     let extcodecopy = KERNEL.global_labels["extcodecopy"];
-    let extcodesize = KERNEL.global_labels["extcodesize"];
 
+    // Put random data in main memory.
+    let mut rng = thread_rng();
+    for i in 0..2000 {
+        interpreter.memory.context_memory[interpreter.context].segments
+            [Segment::MainMemory as usize]
+            .set(i, U256::from(rng.gen::<u8>()));
+    }
+
+    let dest_offset = rng.gen_range(0..3000);
+    let offset = rng.gen_range(0..1500);
+    let size = rng.gen_range(0..1500);
+
+    // Test `extcodecopy`
+    interpreter.offset = extcodecopy;
     interpreter.pop();
+    assert!(interpreter.stack().is_empty());
     interpreter.push(0xDEADBEEFu32.into());
+    interpreter.push(size.into());
+    interpreter.push(offset.into());
+    interpreter.push(dest_offset.into());
     interpreter.push(U256::from_big_endian(address.as_bytes()));
-    interpreter.offset = extcodesize;
     interpreter.generation_state.inputs.contract_code =
         HashMap::from([(keccak(&code), code.clone())]);
     interpreter.run()?;
-    assert_eq!(interpreter.stack(), vec![code.len().into()]);
+
+    assert!(interpreter.stack().is_empty());
+    // Check that the code was correctly copied to memory.
+    for i in 0..size {
+        let memory = interpreter.memory.context_memory[interpreter.context].segments
+            [Segment::MainMemory as usize]
+            .get(dest_offset + i);
+        assert_eq!(
+            memory,
+            code.get(offset + i).copied().unwrap_or_default().into()
+        );
+    }
 
     Ok(())
 }