diff --git a/cores/arduino/wiring_pulse.c b/cores/arduino/wiring_pulse.c
index 3212f13..d6e0434 100644
--- a/cores/arduino/wiring_pulse.c
+++ b/cores/arduino/wiring_pulse.c
@@ -69,22 +69,24 @@ unsigned long pulseInLong(uint8_t pin, uint8_t state, unsigned long timeout)
 	uint8_t port = digitalPinToPort(pin);
 	uint8_t stateMask = (state ? bit : 0);
 
-	unsigned long maxMicros = micros() + timeout;
+	unsigned long startMicros = micros();
 
 	// wait for any previous pulse to end
-	while ((*portInputRegister(port) & bit) == stateMask)
-		if (micros() > maxMicros)
+	while ((*portInputRegister(port) & bit) == stateMask) {
+		if (micros() - startMicros > timeout)
 			return 0;
+	}
 
 	// wait for the pulse to start
-	while ((*portInputRegister(port) & bit) != stateMask)
-		if (micros() > maxMicros)
+	while ((*portInputRegister(port) & bit) != stateMask) {
+		if (micros() - startMicros > timeout)
 			return 0;
+	}
 
 	unsigned long start = micros();
 	// wait for the pulse to stop
 	while ((*portInputRegister(port) & bit) == stateMask) {
-		if (micros() > maxMicros)
+		if (micros() - startMicros > timeout)
 			return 0;
 	}
 	return micros() - start;