diff --git a/hardware/arduino/avr/cores/arduino/Arduino.h b/hardware/arduino/avr/cores/arduino/Arduino.h
index ac775f13c..16dd759b3 100644
--- a/hardware/arduino/avr/cores/arduino/Arduino.h
+++ b/hardware/arduino/avr/cores/arduino/Arduino.h
@@ -114,7 +114,7 @@ typedef unsigned int word;
 
 #define bit(b) (1UL << (b))
 
-typedef uint8_t boolean;
+typedef bool boolean;
 typedef uint8_t byte;
 
 void init(void);
diff --git a/hardware/arduino/sam/cores/arduino/wiring_constants.h b/hardware/arduino/sam/cores/arduino/wiring_constants.h
index a3cd0d00d..9c39b74a9 100644
--- a/hardware/arduino/sam/cores/arduino/wiring_constants.h
+++ b/hardware/arduino/sam/cores/arduino/wiring_constants.h
@@ -92,11 +92,9 @@ typedef unsigned int word;
 
 #define bit(b) (1UL << (b))
 
-// TODO: to be checked
-typedef uint8_t boolean ;
+typedef bool boolean ;
 typedef uint8_t byte ;
 
-
 #ifdef __cplusplus
 } // extern "C"
 #endif // __cplusplus