diff --git a/lib/lcd_hd44780.c b/lib/lcd_hd44780.c
index f30254c..73397c8 100644
--- a/lib/lcd_hd44780.c
+++ b/lib/lcd_hd44780.c
@@ -31,7 +31,7 @@
 /* own libraries */
 #include "global.h" // common methods
 #include "lcd_hd44780.h" // own definitions
-#if LCD_HD44780_I2C
+#if defined(LCD_HD44780_I2C) && LCD_HD44780_I2C
 #include "i2c_master.h" // I²C utilities
 #endif
 
@@ -39,7 +39,7 @@
  *  @note this removes the need to call lcd_hd44780_wait_busy but prevents you to do something else meanwhile, particularly when reading is enabled
  *  @note because I²C is already slow enough, there is no need to wait further
  */
-#if LCD_HD44780_I2C
+#if defined(LCD_HD44780_I2C) && LCD_HD44780_I2C
 #define LCD_HD44780_BUSY_WAIT_INCLUDE 1 // lcd_hd44780_wait_busy works, but the I²C bus is often slower
 #else // LCD_HD44780_I2C
 #define LCD_HD44780_BUSY_WAIT_INCLUDE 1 // you can change this value
@@ -88,7 +88,7 @@
 #define LCD_HD44780_LED (1 << 11) /**< Backlight Cathode */
 /** @} */
 
-#if LCD_HD44780_I2C
+#if defined(LCD_HD44780_I2C) && LCD_HD44780_I2C
 /* I²C backpack PCF8574 GPIO expander pinout:
  * - P0: RS
  * - P1: RnW
@@ -195,7 +195,7 @@ static bool lcd_hd44780_n_2lines = true;
  */
 static void lcd_hd44780_set_signal(uint16_t signals)
 {
-#if LCD_HD44780_I2C
+#if defined(LCD_HD44780_I2C) && LCD_HD44780_I2C
 	if (signals & LCD_HD44780_RS) {
 		lcd_hd44780_i2c_output |= LCD_HD44780_I2C_RS;
 	}
@@ -268,7 +268,7 @@ static void lcd_hd44780_set_signal(uint16_t signals)
  */
 static void lcd_hd44780_clear_signal(uint16_t signals)
 {
-#if LCD_HD44780_I2C
+#if defined(LCD_HD44780_I2C) && LCD_HD44780_I2C
 	if (signals & LCD_HD44780_RS) {
 		lcd_hd44780_i2c_output &= ~LCD_HD44780_I2C_RS;
 	}
@@ -342,7 +342,7 @@ static void lcd_hd44780_clear_signal(uint16_t signals)
  */
 static void lcd_hd44780_flush_signal(void)
 {
-#if LCD_HD44780_I2C
+#if defined(LCD_HD44780_I2C) && LCD_HD44780_I2C
 	i2c_master_slave_write(LCD_HD44780_I2C_PERIPH, lcd_hd44780_i2c_addr, false, &lcd_hd44780_i2c_output, 1); // write the set signals
 #endif
 }
@@ -619,7 +619,7 @@ static void lcd_hd44780_function_set(bool dl_8bit, bool n_2lines, bool f_5x10)
 bool lcd_hd44780_setup(bool n_2lines, bool f_5x10)
 {
 	sleep_ms(40 + 2); // wait for display to initialise after power on: 15 ms for VCC > 4.5 V, 40 ms for VCC > 2.7 V
-#ifdef LCD_HD44780_I2C
+#if defined(LCD_HD44780_I2C) && LCD_HD44780_I2C
 	// configure I²C peripheral
 	if (!i2c_master_check_signals(LCD_HD44780_I2C_PERIPH)) { // check if there are pull-ups to operator I²C
 		return false;
@@ -694,14 +694,12 @@ bool lcd_hd44780_setup(bool n_2lines, bool f_5x10)
 	lcd_hd44780_entry_mode_set(true, false); // entry mode set
 	lcd_hd44780_wait_busy(LCD_HD44780_BUSY_WAIT_SHORT);
 
-#if LCD_HD44780_I2C
 	return true; // I²C configuration succeeded
-#endif
 }
 
 void lcd_hd44780_release(void)
 {
-#if LCD_HD44780_I2C
+#if defined(LCD_HD44780_I2C) && LCD_HD44780_I2C
 	i2c_master_release(LCD_HD44780_I2C_PERIPH); // release I²C peripheral
 #else // LCD_HD44780_I2C
 	// switch back GPIO back to input