diff --git a/examples/NEO-M8P-2/Example2_StartRTCMBase/Example2_StartRTCMBase.ino b/examples/NEO-M8P-2/Example2_StartRTCMBase/Example2_StartRTCMBase.ino
index a3ea14d..4b21af1 100644
--- a/examples/NEO-M8P-2/Example2_StartRTCMBase/Example2_StartRTCMBase.ino
+++ b/examples/NEO-M8P-2/Example2_StartRTCMBase/Example2_StartRTCMBase.ino
@@ -29,7 +29,30 @@
 #include <Wire.h> //Needed for I2C to GNSS
 
 #include <SparkFun_u-blox_GNSS_Arduino_Library.h> //http://librarymanager/All#SparkFun_u-blox_GNSS
-SFE_UBLOX_GNSS myGNSS;
+
+class MY_SFE_UBLOX_GNSS : public SFE_UBLOX_GNSS {
+
+  friend SFE_UBLOX_GNSS;
+
+public:
+  MY_SFE_UBLOX_GNSS()
+  {
+    setUserContext(this);
+  }
+
+protected:
+  void myProcessRTCM(uint8_t incoming)
+  {
+    //Let's just pretty-print the HEX values for now
+    if (rtcmFrameCounter % 16 == 0) Serial.println();
+    Serial.print(F(" "));
+    if (incoming < 0x10) Serial.print(F("0"));
+    Serial.print(incoming, HEX);
+  }
+
+};
+
+MY_SFE_UBLOX_GNSS myGNSS;
 
 void setup()
 {
@@ -156,9 +179,11 @@ void loop()
 //Useful for passing the RTCM correction data to a radio, Ntrip broadcaster, etc.
 void SFE_UBLOX_GNSS::processRTCM(uint8_t incoming)
 {
-  //Let's just pretty-print the HEX values for now
-  if (myGNSS.rtcmFrameCounter % 16 == 0) Serial.println();
-  Serial.print(F(" "));
-  if (incoming < 0x10) Serial.print(F("0"));
-  Serial.print(incoming, HEX);
+  MY_SFE_UBLOX_GNSS *me;
+
+  // jump into our instance
+  if ((me = static_cast<MY_SFE_UBLOX_GNSS *>(this)) != NULL)
+  {
+    me->myProcessRTCM(incoming);
+  }
 }
diff --git a/src/SparkFun_u-blox_GNSS_Arduino_Library.cpp b/src/SparkFun_u-blox_GNSS_Arduino_Library.cpp
index 460dbce..03aefe9 100644
--- a/src/SparkFun_u-blox_GNSS_Arduino_Library.cpp
+++ b/src/SparkFun_u-blox_GNSS_Arduino_Library.cpp
@@ -633,6 +633,18 @@ size_t SFE_UBLOX_GNSS::getPacketCfgSpaceRemaining()
   return (packetCfgPayloadSize - packetCfg.len);
 }
 
+// Sets user context
+void SFE_UBLOX_GNSS::setUserContext(void *userContext)
+{
+  _userContext = userContext;
+}
+
+// Retrive user context
+void *SFE_UBLOX_GNSS::getUserContext(void)
+{
+  return _userContext;
+}
+
 // Initialize the I2C port
 bool SFE_UBLOX_GNSS::begin(TwoWire &wirePort, uint8_t deviceAddress, uint16_t maxWait, bool assumeSuccess)
 {
diff --git a/src/SparkFun_u-blox_GNSS_Arduino_Library.h b/src/SparkFun_u-blox_GNSS_Arduino_Library.h
index c83f002..6726127 100644
--- a/src/SparkFun_u-blox_GNSS_Arduino_Library.h
+++ b/src/SparkFun_u-blox_GNSS_Arduino_Library.h
@@ -682,6 +682,10 @@ class SFE_UBLOX_GNSS
   bool setPacketCfgPayloadSize(size_t payloadSize); // Set packetCfgPayloadSize
   size_t getPacketCfgSpaceRemaining();              // Returns the number of free bytes remaining in packetCfgPayload
 
+  // User context
+  void setUserContext(void *userContext);          // Sets user context
+  void *getUserContext(void);                      // Retrive user context
+
   // Begin communication with the GNSS. Advanced users can assume success if required. Useful if the port is already outputting messages at high navigation rate.
   // Begin will then return true if "signs of life" have been seen: reception of _any_ valid UBX packet or _any_ valid NMEA header.
   // By default use the default I2C address, and use Wire port
@@ -1708,6 +1712,7 @@ class SFE_UBLOX_GNSS
   SPIClass *_spiPort; // The instance of SPIClass
   uint8_t _csPin;     // The chip select pin
   uint32_t _spiSpeed; // The speed to use for SPI (Hz)
+  void *_userContext; // Custom user context as callback context
 
   uint8_t _gpsI2Caddress = 0x42; // Default 7-bit unshifted address of the ublox 6/7/8/M8/F9 series
   // This can be changed using the ublox configuration software