Fix typo

README.md

@@ -475,7 +475,7 @@ Explanation of the values specific for the Opa plugin:
 | cntData | Name which data counter to query. A list of possible values can be found below.
 
 
-> NOTE     As perfevent counters are usually always monotonic, the delta attribute is by default set to true for all sensors. One has to explicitly set delta to "off" for a sensor to overwrite this behaviour.
+> NOTE     As opa counters are usually always monotonic, the delta attribute is by default set to true for all sensors. One has to explicitly set delta to "off" for a sensor to overwrite this behaviour.
 
 ### counterData <a name="opaCounterData"></a>
 

src/includes/SensorBase.h

@@ -160,7 +160,7 @@ public:
 	 * @param maxValue    Maximum possible value of the reading; required for the
 	 *                    delta computation to detect an overflow.
 	 */
-	void storeReading(reading_t rawReading, double factor=1.0, unsigned long long maxValue=LLONG_MAX) {
+	void storeReading(reading_t rawReading, double factor=1.0, long long maxValue=LLONG_MAX) {
 		reading_t reading = rawReading;
 		if( _delta ) {
 		    if (!_firstReading) {