diff --git a/PCF8574.cpp b/PCF8574.cpp
index 1813f7e..c6f6bf7 100644
--- a/PCF8574.cpp
+++ b/PCF8574.cpp
@@ -22,7 +22,7 @@ PCF8574::PCF8574(uint8_t address, uint8_t interruptPin,  void (*interruptFunctio
 	_usingInterrupt = true;
 };
 
-#if !defined(__AVR) && !defined(STM32F1)
+#if !defined(__AVR) && !defined(__STM32F1__)
 	/**
 	 * Constructor
 	 * @param address: i2c address
@@ -59,7 +59,7 @@ PCF8574::PCF8574(uint8_t address, uint8_t interruptPin,  void (*interruptFunctio
  * wake up i2c controller
  */
 void PCF8574::begin(){
-	#if !defined(__AVR) && !defined(STM32F1)
+	#if !defined(__AVR) && !defined(__STM32F1__)
 		Wire.begin(_sda, _scl);
 	#else
 	//			Default pin for AVR and Arduino STM32 some problem on software emulation
diff --git a/PCF8574.h b/PCF8574.h
index 449c7c4..0291908 100644
--- a/PCF8574.h
+++ b/PCF8574.h
@@ -92,7 +92,7 @@ public:
 private:
 	uint8_t _address;
 
-	#if !defined(__AVR) && !defined(STM32F1)
+	#if defined(__AVR) || defined(__STM32F1__)
 		uint8_t _sda;
 		uint8_t _scl;
 	#else