diff --git a/src/cpu.rs b/src/cpu.rs
index eaa6e78..034cc39 100644
--- a/src/cpu.rs
+++ b/src/cpu.rs
@@ -639,37 +639,45 @@ impl CPU {
             },
             // Increment by 1
             Opcode::INC(affect_flags, register) => {
-                let prev_value = self.registers.get(register);
-                self.registers.increment(register, 1);
+                self.registers.increment(Register::PC, 1);
+                let mut prev_value = 0;
+                let mut result = 0;
+                if register.is_8bit() {
+                    prev_value = self.registers.get_8bit(register);
+                    self.registers.increment(register, 1);
+                    result = self.registers.get_8bit(register);
+                } else {
+                    let addr = self.registers.get(register);
+                    prev_value = bus.read(addr);
+                    bus.write(addr, prev_value + 1);
+                    result = bus.read(addr);
+                }
                 if affect_flags {
                     self.registers.set_flag(FlagRegister::Substract, false);
-                    let mut byte_compare = 0;
-                    match register.is_8bit() {
-                        true => byte_compare = prev_value.to_be_bytes()[1],
-                        false => byte_compare = prev_value.to_be_bytes()[0],
-                    }
-                    self.registers.set_flag(FlagRegister::HalfCarry, add_half_carry(byte_compare, 1));
-                    let result = self.registers.get(register);
+                    self.registers.set_flag(FlagRegister::HalfCarry, add_half_carry(prev_value, 1));
                     self.registers.set_flag(FlagRegister::Zero, result == 0);
                 }
-                self.registers.increment(Register::PC, 1);
             },
             // Decrement by 1
             Opcode::DEC(affect_flags, register) => {
-                let prev_value = self.registers.get(register);
-                self.registers.decrement(register, 1);
+                self.registers.increment(Register::PC, 1);
+                let mut prev_value = 0;
+                let mut result = 0;
+                if register.is_8bit() {
+                    prev_value = self.registers.get_8bit(register);
+                    self.registers.decrement(register, 1);
+                    result = self.registers.get_8bit(register);
+                } else {
+                    let addr = self.registers.get(register);
+                    prev_value = bus.read(addr);
+                    bus.write(addr, prev_value - 1);
+                    result = bus.read(addr);
+                }
                 if affect_flags {
                     self.registers.set_flag(FlagRegister::Substract, true);
-                    let mut byte_compare = 0;
-                    match register.is_8bit() {
-                        true => byte_compare = prev_value.to_be_bytes()[1],
-                        false => byte_compare = prev_value.to_be_bytes()[0],
-                    }
-                    self.registers.set_flag(FlagRegister::HalfCarry, sub_half_carry(byte_compare, 1));
-                    let result = self.registers.get(register);
+                    self.registers.set_flag(FlagRegister::HalfCarry, sub_half_carry(prev_value, 1));
                     self.registers.set_flag(FlagRegister::Zero, result == 0);
                 }
-                self.registers.increment(Register::PC, 1);
             },
             // Jump to address
             Opcode::JP(params) => match params {
@@ -2335,12 +2343,14 @@ mod tests {
         assert_eq!(cpu.registers.get_flag(FlagRegister::HalfCarry), true);
         assert_eq!(cpu.registers.get(Register::PC), 0x101);
         let mut cpu = CPU::new();
-        cpu.registers.set(Register::HL, 0b0000111111111111);
+        let addr = 0xC000;
+        cpu.registers.set(Register::HL, addr);
+        bus.write(addr, 0b00001111);
         cpu.exec(Opcode::INC(true, Register::HL), &mut bus);
         assert_eq!(cpu.registers.get_flag(FlagRegister::Zero), false);
         assert_eq!(cpu.registers.get_flag(FlagRegister::Substract), false);
         assert_eq!(cpu.registers.get_flag(FlagRegister::HalfCarry), true);
-        assert_eq!(cpu.registers.get(Register::HL), 0b0001000000000000);
+        assert_eq!(bus.read(addr), 0b00010000);
         assert_eq!(cpu.registers.get(Register::PC), 0x101);
     }
 
@@ -2364,12 +2374,14 @@ mod tests {
         assert_eq!(cpu.registers.get(Register::A), 0b00001111);
         assert_eq!(cpu.registers.get(Register::PC), 0x101);
         let mut cpu = CPU::new();
-        cpu.registers.set(Register::HL, 0b0001000000000000);
+        let addr = 0xC000;
+        cpu.registers.set(Register::HL, addr);
+        bus.write(addr, 0b00010000);
         cpu.exec(Opcode::DEC(true, Register::HL), &mut bus);
         assert_eq!(cpu.registers.get_flag(FlagRegister::Zero), false);
         assert_eq!(cpu.registers.get_flag(FlagRegister::Substract), true);
         assert_eq!(cpu.registers.get_flag(FlagRegister::HalfCarry), true);
-        assert_eq!(cpu.registers.get(Register::HL), 0b0000111111111111);
+        assert_eq!(bus.read(addr), 0b00001111);
         assert_eq!(cpu.registers.get(Register::PC), 0x101);
     }