diff --git a/io.hpp b/io.hpp
index 7b91716..cf5f519 100644
--- a/io.hpp
+++ b/io.hpp
@@ -7,25 +7,42 @@
 //////////////////////////////////////////////////////////////////////////
 // Preprocessor defines
 
-#define GPIO_32 \
-	defined(__AVR_ATmega32__) || defined(__AVR_ATmega32A__) || defined(__AVR_ATmega644P__) || \
-	    defined(__AVR_ATmega1284P__)
-#define GPIO_23 \
-	defined(__AVR_ATmega8__) || defined(__AVR_ATmega8A__) || defined(__AVR_ATmega168A__) || defined(__AVR_ATmega328P__)
-#define GPIO_6 defined(__AVR_ATtiny13A__) || defined(__AVR_ATtiny85__)
+#if defined(__AVR_ATmega32__) || defined(__AVR_ATmega32A__) || defined(__AVR_ATmega644P__) || \
+    defined(__AVR_ATmega1284P__)
+#define GPIO_32
+#endif
 
-#define HARDWARE_TOGGLE \
-	defined(__AVR_ATmega644P__) || defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega168A__) || \
-	    defined(__AVR_ATmega328P__) || defined(__AVR_ATtiny13A__) || defined(__AVR_ATtiny85__)
+#if defined(__AVR_ATmega8__) || defined(__AVR_ATmega8A__) || defined(__AVR_ATmega168A__) || defined(__AVR_ATmega328P__)
+#define GPIO_23
+#endif
 
-#define PORT_A_AVAILABLE GPIO_32
-#define PORT_B_AVAILABLE GPIO_32 || GPIO_23 || GPIO_6
-#define PORT_C_AVAILABLE GPIO_32 || GPIO_23
-#define PORT_D_AVAILABLE GPIO_32 || GPIO_23
+#if defined(__AVR_ATtiny13A__) || defined(__AVR_ATtiny85__)
+#define GPIO_6
+#endif
 
-#define PIN_B6_AVAILABLE GPIO_32 || GPIO_23
-#define PIN_B7_AVAILABLE GPIO_32 || GPIO_23
-#define PIN_C7_AVAILABLE GPIO_32
+#if defined(__AVR_ATmega644P__) || defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega168A__) || \
+    defined(__AVR_ATmega328P__) || defined(__AVR_ATtiny13A__) || defined(__AVR_ATtiny85__)
+#define HARDWARE_TOGGLE
+#endif
+
+#ifdef GPIO_32
+#define PORT_A_AVAILABLE
+#endif
+
+#if defined(GPIO_32) || defined(GPIO_23) || defined(GPIO_6)
+#define PORT_B_AVAILABLE
+#endif
+
+#if defined(GPIO_32) || defined(GPIO_23)
+#define PORT_C_AVAILABLE
+#define PORT_D_AVAILABLE
+#define PIN_B6_AVAILABLE
+#define PIN_B7_AVAILABLE
+#endif
+
+#if defined(GPIO_32)
+#define PIN_C7_AVAILABLE
+#endif
 
 #define FORCE_INLINE __attribute__((always_inline))
 
@@ -37,7 +54,7 @@ namespace io {
 enum class Dir { IN, OUT };
 
 enum class P {
-#if PORT_A_AVAILABLE
+#ifdef PORT_A_AVAILABLE
 	A0 = 0x00,
 	A1 = 0x01,
 	A2 = 0x02,
@@ -48,22 +65,22 @@ enum class P {
 	A7 = 0x07,
 #endif
 
-#if PORT_B_AVAILABLE
+#ifdef PORT_B_AVAILABLE
 	B0 = 0x10,
 	B1 = 0x11,
 	B2 = 0x12,
 	B3 = 0x13,
 	B4 = 0x14,
 	B5 = 0x15,
-#if PIN_B6_AVAILABLE
+#ifdef PIN_B6_AVAILABLE
 	B6 = 0x16,
 #endif
-#if PIN_B7_AVAILABLE
+#ifdef PIN_B7_AVAILABLE
 	B7 = 0x17,
 #endif
 #endif
 
-#if PORT_C_AVAILABLE
+#ifdef PORT_C_AVAILABLE
 	C0 = 0x20,
 	C1 = 0x21,
 	C2 = 0x22,
@@ -71,12 +88,12 @@ enum class P {
 	C4 = 0x24,
 	C5 = 0x25,
 	C6 = 0x26,
-#if PIN_C7_AVAILABLE
+#ifdef PIN_C7_AVAILABLE
 	C7 = 0x27,
 #endif
 #endif
 
-#if PORT_D_AVAILABLE
+#ifdef PORT_D_AVAILABLE
 	D0 = 0x30,
 	D1 = 0x31,
 	D2 = 0x32,
@@ -89,16 +106,16 @@ enum class P {
 };
 
 enum class Bus {
-#if PORT_A_AVAILABLE
+#ifdef PORT_A_AVAILABLE
 	A = 0x00,
 #endif
-#if PORT_B_AVAILABLE
+#ifdef PORT_B_AVAILABLE
 	B = 0x01,
 #endif
-#if PORT_C_AVAILABLE
+#ifdef PORT_C_AVAILABLE
 	C = 0x02,
 #endif
-#if PORT_D_AVAILABLE
+#ifdef PORT_D_AVAILABLE
 	D = 0x03,
 #endif
 };
@@ -108,7 +125,7 @@ enum class Bus {
 
 namespace detail {
 
-#if PORT_A_AVAILABLE
+#ifdef PORT_A_AVAILABLE
 static constexpr volatile uint8_t *PORT_A_DIR_REG = &DDRA;
 static constexpr volatile uint8_t *PORT_A_OUTPUT_REG = &PORTA;
 static constexpr volatile uint8_t *PORT_A_INPUT_REG = &PINA;
@@ -118,7 +135,7 @@ static constexpr volatile uint8_t *PORT_A_OUTPUT_REG = nullptr;
 static constexpr volatile uint8_t *PORT_A_INPUT_REG = nullptr;
 #endif
 
-#if PORT_B_AVAILABLE
+#ifdef PORT_B_AVAILABLE
 static constexpr volatile uint8_t *PORT_B_DIR_REG = &DDRB;
 static constexpr volatile uint8_t *PORT_B_OUTPUT_REG = &PORTB;
 static constexpr volatile uint8_t *PORT_B_INPUT_REG = &PINB;
@@ -128,7 +145,7 @@ static constexpr volatile uint8_t *PORT_B_OUTPUT_REG = nullptr;
 static constexpr volatile uint8_t *PORT_B_INPUT_REG = nullptr;
 #endif
 
-#if PORT_C_AVAILABLE
+#ifdef PORT_C_AVAILABLE
 static constexpr volatile uint8_t *PORT_C_DIR_REG = &DDRC;
 static constexpr volatile uint8_t *PORT_C_OUTPUT_REG = &PORTC;
 static constexpr volatile uint8_t *PORT_C_INPUT_REG = &PINC;
@@ -138,7 +155,7 @@ static constexpr volatile uint8_t *PORT_C_OUTPUT_REG = nullptr;
 static constexpr volatile uint8_t *PORT_C_INPUT_REG = nullptr;
 #endif
 
-#if PORT_D_AVAILABLE
+#ifdef PORT_D_AVAILABLE
 static constexpr volatile uint8_t *PORT_D_DIR_REG = &DDRD;
 static constexpr volatile uint8_t *PORT_D_OUTPUT_REG = &PORTD;
 static constexpr volatile uint8_t *PORT_D_INPUT_REG = &PIND;
@@ -259,7 +276,7 @@ class Pin {
 
 	static inline void toggle() FORCE_INLINE
 	{
-#if HARDWARE_TOGGLE
+#ifdef HARDWARE_TOGGLE
 		constexpr auto bus = detail::getBus(pin);
 		constexpr auto pinReg = detail::getPIN(bus);
 		constexpr auto pinBit = detail::getPin(pin);
@@ -342,7 +359,7 @@ class Port {
 
 	static inline void invert() FORCE_INLINE
 	{
-#if HARDWARE_TOGGLE
+#ifdef HARDWARE_TOGGLE
 		constexpr auto pinReg = detail::getPIN(port);
 
 		*pinReg = 0xFF;