diff --git a/evm_arithmetization/src/cpu/kernel/asm/core/exception.asm b/evm_arithmetization/src/cpu/kernel/asm/core/exception.asm
index fb260a20e..9aae5983b 100644
--- a/evm_arithmetization/src/cpu/kernel/asm/core/exception.asm
+++ b/evm_arithmetization/src/cpu/kernel/asm/core/exception.asm
@@ -395,7 +395,7 @@ gas_cost_for_opcode:
     BYTES @GAS_JUMPDEST  // 0x5b, JUMPDEST
     BYTES 0  // 0x5c, TLOAD
     BYTES 0  // 0x5d, TSTORE
-    BYTES 0  // 0x5e, invalid
+    BYTES 0  // 0x5e, MCOPY
 
     BYTES @GAS_BASE // 0x5f, PUSH0
     %rep 32 // 0x60-0x7f, PUSH1-PUSH32
diff --git a/evm_arithmetization/src/cpu/kernel/asm/core/syscall.asm b/evm_arithmetization/src/cpu/kernel/asm/core/syscall.asm
index f74b0d529..87c01dc7f 100644
--- a/evm_arithmetization/src/cpu/kernel/asm/core/syscall.asm
+++ b/evm_arithmetization/src/cpu/kernel/asm/core/syscall.asm
@@ -90,7 +90,7 @@ global syscall_jumptable:
     JUMPTABLE panic // jumpdest is implemented natively
     JUMPTABLE sys_tload
     JUMPTABLE sys_tstore
-    JUMPTABLE panic // 0x5e is an invalid opcode
+    JUMPTABLE sys_mcopy
     JUMPTABLE panic // 0x5f is an invalid opcode
 
     // 0x60-0x6f
diff --git a/evm_arithmetization/src/cpu/kernel/constants/exc_bitfields.rs b/evm_arithmetization/src/cpu/kernel/constants/exc_bitfields.rs
index 9ffc626f5..0abc84e70 100644
--- a/evm_arithmetization/src/cpu/kernel/constants/exc_bitfields.rs
+++ b/evm_arithmetization/src/cpu/kernel/constants/exc_bitfields.rs
@@ -47,7 +47,6 @@ pub(crate) const INVALID_OPCODES_USER: U256 = u256_from_set_index_ranges(&[
     0x1e..=0x1f,
     0x21..=0x2f,
     0x4a..=0x4f,
-    0x5e..=0x5e,
     0xa5..=0xef,
     0xf6..=0xf9,
     0xfb..=0xfc,