diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8d72e13..75cc74b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - fix **float getShuntVoltage()** for negative values, kudos to aguilerabr
 - add **int getMaxShuntVoltage()**, depends on GAIN (Table 7).
 - removed default for **setGain()** as it was not sensors default.
+- update readme.md
 
 ----
 
diff --git a/INA219.cpp b/INA219.cpp
index df5a419..d791d00 100644
--- a/INA219.cpp
+++ b/INA219.cpp
@@ -167,6 +167,7 @@ bool INA219::setGain(uint8_t factor)
   }
   uint16_t config = _readRegister(INA219_CONFIGURATION);
   config &= ~INA219_CONF_PROG_GAIN;
+  //  factor == 1 ==> mask = 00
   if      (factor == 2) config |= (1 << 11);
   else if (factor == 4) config |= (2 << 11);
   else if (factor == 8) config |= (3 << 11);
diff --git a/README.md b/README.md
index 18d6a97..bfa8c04 100644
--- a/README.md
+++ b/README.md
@@ -160,8 +160,8 @@ Determines the shunt voltage range. 40, 80, 160 or 320 mV.
 Returns false if factor is not a valid value.
 Returns false if it could not write settings to device.
 - **uint8_t getGain()** returns set factor.
-- **int getMaxShuntVoltage()** returns 40, 80, 160 or 320 (default).
-Value in millivolts mV.
+- **int getMaxShuntVoltage()** returns 40, 80, 160 or 320 (mV).
+320 is the sensors default.
 
 
 #### Configuration BUS and SHUNT