diff --git a/lib/obp60task/PageVoltage.cpp b/lib/obp60task/PageVoltage.cpp
index 77af4ca..cc1f9bb 100644
--- a/lib/obp60task/PageVoltage.cpp
+++ b/lib/obp60task/PageVoltage.cpp
@@ -127,7 +127,7 @@ public:
         }
         
         // Logging voltage value
-        if (raw == NULL) return;
+        if (raw == 0) return;
         LOG_DEBUG(GwLog::LOG,"Drawing at PageVoltage, Type:%s %s:=%f", batType, name1.c_str(), raw);
 
         // Draw page
diff --git a/lib/obp60task/RTClib.cpp b/lib/obp60task/RTClib.cpp
index 8c5429c..ebc989f 100644
--- a/lib/obp60task/RTClib.cpp
+++ b/lib/obp60task/RTClib.cpp
@@ -486,7 +486,7 @@ uint8_t RTC_BQ32000::readRegister(uint8_t address) {
     return Wire.read();
 }
 
-uint8_t RTC_BQ32000::writeRegister(uint8_t address, uint8_t value) {
+void RTC_BQ32000::writeRegister(uint8_t address, uint8_t value) {
     /* Write the given value to the register at the given address.
      */
     Wire.beginTransmission(BQ32000_ADDRESS);
@@ -513,4 +513,4 @@ DateTime RTC_Millis::now() {
     return offset + millis() / 1000;
 }
 
-////////////////////////////////////////////////////////////////////////////////
\ No newline at end of file
+////////////////////////////////////////////////////////////////////////////////
diff --git a/lib/obp60task/RTClib.h b/lib/obp60task/RTClib.h
index a99e791..137c51f 100644
--- a/lib/obp60task/RTClib.h
+++ b/lib/obp60task/RTClib.h
@@ -182,7 +182,7 @@ public:
 
     // utility functions:
     static uint8_t readRegister(uint8_t address);
-    static uint8_t writeRegister(uint8_t address, uint8_t value);
+    static void writeRegister(uint8_t address, uint8_t value);
     static uint8_t bcd2bin (uint8_t val) { return val - 6 * (val >> 4); }
     static uint8_t bin2bcd (uint8_t val) { return val + 6 * (val / 10); }
 };