diff --git a/optimism/src/mips/interpreter.rs b/optimism/src/mips/interpreter.rs
index d417d0523e..a025c75bc7 100644
--- a/optimism/src/mips/interpreter.rs
+++ b/optimism/src/mips/interpreter.rs
@@ -1054,7 +1054,13 @@ pub fn interpret_rtype<Env: InterpreterEnv>(env: &mut Env, instr: RTypeInstructi
             env.set_next_instruction_pointer(next_instruction_pointer + Env::constant(4u32));
             return;
         }
-        RTypeInstruction::MoveToLo => (),
+        RTypeInstruction::MoveToLo => {
+            let rs = env.read_register(&rs);
+            env.write_register(&Env::constant(REGISTER_LO as u32), rs);
+            env.set_instruction_pointer(next_instruction_pointer.clone());
+            env.set_next_instruction_pointer(next_instruction_pointer + Env::constant(4u32));
+            return;
+        }
         RTypeInstruction::Multiply => (),
         RTypeInstruction::MultiplyUnsigned => {
             let rs = env.read_register(&rs);