diff --git a/libraries/MySensors/MySensor.cpp b/libraries/MySensors/MySensor.cpp
index f8a49bd..7c2933f 100644
--- a/libraries/MySensors/MySensor.cpp
+++ b/libraries/MySensors/MySensor.cpp
@@ -472,7 +472,7 @@ void wakeUp()	 //place to send the interrupts
 	continueTimer = false;
 }
 
-void MySensor::internalSleep(int ms) {
+void MySensor::internalSleep(unsigned long ms) {
 	while (continueTimer && ms >= 8000) { LowPower.powerDown(SLEEP_8S, ADC_OFF, BOD_OFF); ms -= 8000; }
 	if (continueTimer && ms >= 4000)    { LowPower.powerDown(SLEEP_4S, ADC_OFF, BOD_OFF); ms -= 4000; }
 	if (continueTimer && ms >= 2000)    { LowPower.powerDown(SLEEP_2S, ADC_OFF, BOD_OFF); ms -= 2000; }
@@ -485,7 +485,7 @@ void MySensor::internalSleep(int ms) {
 	if (continueTimer && ms >= 16)      { LowPower.powerDown(SLEEP_15Ms, ADC_OFF, BOD_OFF); ms -= 15; }
 }
 
-void MySensor::sleep(int ms) {
+void MySensor::sleep(unsigned long ms) {
 	// Let serial prints finish (debug, log etc)
 	Serial.flush();
 	RF24::powerDown();
@@ -493,7 +493,7 @@ void MySensor::sleep(int ms) {
 	internalSleep(ms);
 }
 
-bool MySensor::sleep(int interrupt, int mode, int ms) {
+bool MySensor::sleep(int interrupt, int mode, unsigned long  ms) {
 	// Let serial prints finish (debug, log etc)
 	bool pinTriggeredWakeup = true;
 	Serial.flush();
diff --git a/libraries/MySensors/MySensor.h b/libraries/MySensors/MySensor.h
index 6e16071..38f16e4 100644
--- a/libraries/MySensors/MySensor.h
+++ b/libraries/MySensors/MySensor.h
@@ -203,7 +203,7 @@ class MySensor : public RF24
 	 * Sleep (PowerDownMode) the Arduino and radio. Wake up on timer.
 	 * @param ms Number of milliseconds to sleep.
 	 */
-	void sleep(int ms);
+	void sleep(unsigned long ms);
 
 	/**
 	 * Sleep (PowerDownMode) the Arduino and radio. Wake up on timer or pin change.
@@ -214,7 +214,7 @@ class MySensor : public RF24
 	 * @param ms Number of milliseconds to sleep or 0 to sleep forever
 	 * @return true if wake up was triggered by pin change and false means timer woke it up.
 	 */
-	bool sleep(int interrupt, int mode, int ms=0);
+	bool sleep(int interrupt, int mode, unsigned long ms=0);
 
 	/**
 	 * getInternalTemp
@@ -264,7 +264,7 @@ class MySensor : public RF24
 	uint8_t getChildRoute(uint8_t childId);
 	void addChildRoute(uint8_t childId, uint8_t route);
 	void removeChildRoute(uint8_t childId);
-	void internalSleep(int ms);
+	void internalSleep(unsigned long ms);
 };
 
 #endif