diff --git a/src/kernel/exception.rs b/src/kernel/exception.rs
index 61b1544..24555fe 100644
--- a/src/kernel/exception.rs
+++ b/src/kernel/exception.rs
@@ -78,10 +78,7 @@ fn syscall(machine: &Machine) -> Result<MachineOk, MachineError> {
             // load buffer
             let mut buffer = "".to_string();
             for i in 0..size {
-                match char::from_digit(machine.read_memory(1, (address + i) as usize) as u32, 2) {
-                    Some(c) => buffer.push(c),
-                    None => todo!() // Throw a proper error
-                }
+                buffer.push((machine.read_memory(1, (address + i) as usize)) as u8 as char);
             }
 
             if f as u8 == CONSOLE_OUTPUT {
@@ -121,4 +118,55 @@ fn syscall(machine: &Machine) -> Result<MachineOk, MachineError> {
         SC_DEBUG => todo!(),
         _ => todo!()
     }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::kernel::exception::{SC_SHUTDOWN, SC_WRITE};
+    use crate::simulator::instruction::Instruction;
+    use crate::simulator::machine::Machine;
+
+    #[test]
+    fn test_sc_shutdown() {
+        let mut machine = Machine::init_machine();
+        machine.write_int_register(17, SC_SHUTDOWN as i64); // Set type to shutdown
+        let ecall = Instruction::new(0b000000000000_00000_000_00000_1110011);
+
+        machine.write_memory(4, 0, 0b000000000000_00000_000_00000_1110011); // ecall
+        machine.write_memory(4, 4, 0b000000001010_00000_000_00001_0010011); // r1 <- 10
+
+        machine.run();
+        // If the machine was stopped with no error, the shutdown worked
+        assert_ne!(machine.read_int_register(1), 10); // Check if the next instruction was executed
+    }
+
+    // This test print HELLO in the console
+    #[test]
+    #[ignore]
+    fn test_sc_print() {
+        let mut machine = Machine::init_machine();
+
+        let address = machine.read_int_register(10);
+        // Write string 'HELLO' in memory
+        machine.write_memory(1, 4000, 72);
+        machine.write_memory(1, 4001, 69);
+        machine.write_memory(1, 4002, 76);
+        machine.write_memory(1, 4003, 76);
+        machine.write_memory(1, 4004, 79);
+
+
+        machine.write_int_register(10, 4000); // String address
+        machine.write_int_register(11, 5); // String size
+        machine.write_int_register(12, 1); // Console output
+
+        machine.write_memory(4, 0, 0b000000000000_00000_000_00000_1110011); // ecall
+        machine.write_int_register(17, SC_WRITE as i64); // Set type to write
+
+        machine.write_memory(4, 4, 0b000000000000_00000_000_10001_0010011); // r17 <- SC_SHUTDOWN
+        machine.write_memory(4, 8, 0b000000000000_00000_000_00000_1110011); // ecall
+
+
+        machine.run();
+    }
+
 }
\ No newline at end of file
diff --git a/src/simulator/machine.rs b/src/simulator/machine.rs
index 9e4b4af..7862785 100644
--- a/src/simulator/machine.rs
+++ b/src/simulator/machine.rs
@@ -298,7 +298,7 @@ impl Machine {
 			RISCV_JAL => {
 				self.int_reg.set_reg(inst.rd, self.pc as i64);
 				self.pc = (self.pc as i64 + inst.imm21_1_signed as i64 - 4) as u64;
-				Ok((MachineOk::Ok))
+				Ok(MachineOk::Ok)
 			},
 
 			// Treatment for: JUMP AND LINK REGISTER INSTRUCTIONS (indirect jump)
@@ -306,7 +306,7 @@ impl Machine {
 				let tmp = self.pc;
 				self.pc = (self.int_reg.get_reg(inst.rs1) + inst.imm12_I_signed as i64) as u64 & 0xfffffffe;
 				self.int_reg.set_reg(inst.rd, tmp as i64);
-				Ok((MachineOk::Ok))
+				Ok(MachineOk::Ok)
 			},
 
   			// Treatment for: BRANCH INSTRUCTIONS