diff --git a/src/ESP32RotaryEncoder.cpp b/src/ESP32RotaryEncoder.cpp
index 1987864..681ac9c 100644
--- a/src/ESP32RotaryEncoder.cpp
+++ b/src/ESP32RotaryEncoder.cpp
@@ -21,6 +21,22 @@
   #endif
 #endif
 
+static const DRAM_ATTR char *LOG_TAG = "ESP32RotaryEncoder";
+
+typedef enum {
+    LEFT  = -1,
+    STILL =  0,
+    RIGHT =  1
+} Rotation;
+
+static const Rotation encoderStates[16] = {
+  STILL, LEFT,  RIGHT, STILL,
+  RIGHT, STILL, STILL, LEFT,
+  LEFT,  STILL, STILL, RIGHT,
+  STILL, RIGHT, LEFT,  STILL
+};
+
+
 RotaryEncoder::RotaryEncoder( uint8_t encoderPinA, uint8_t encoderPinB, int8_t buttonPin, int8_t vccPin, uint8_t encoderSteps )
   : encoderPinA{ encoderPinA },
     encoderPinB{ encoderPinB },
@@ -332,10 +348,10 @@ void RotaryEncoder::setEncoderValue( long newValue )
 
 void ARDUINO_ISR_ATTR RotaryEncoder::loop()
 {
-  if( callbackEncoderChanged != NULL && encoderChanged() )
+  if( callbackEncoderChanged != nullptr && encoderChanged() )
     callbackEncoderChanged( getEncoderValue() );
 
-  if( callbackButtonPressed != NULL && buttonPressed() )
+  if( callbackButtonPressed != nullptr && buttonPressed() )
     callbackButtonPressed( buttonPressedDuration );
 }
 
diff --git a/src/ESP32RotaryEncoder.h b/src/ESP32RotaryEncoder.h
index 4ad62dc..c193426 100644
--- a/src/ESP32RotaryEncoder.h
+++ b/src/ESP32RotaryEncoder.h
@@ -230,23 +230,8 @@ class RotaryEncoder {
     void loop();
 
   private:
-    const char *LOG_TAG = "ESP32RotaryEncoder";
-
-    EncoderCallback callbackEncoderChanged = NULL;
-    ButtonCallback callbackButtonPressed = NULL;
-
-    typedef enum {
-        LEFT  = -1,
-        STILL =  0,
-        RIGHT =  1
-    } Rotation;
-
-    Rotation encoderStates[16] = {
-      STILL, LEFT,  RIGHT, STILL,
-      RIGHT, STILL, STILL, LEFT,
-      LEFT,  STILL, STILL, RIGHT,
-      STILL, RIGHT, LEFT,  STILL
-    };
+    EncoderCallback callbackEncoderChanged = nullptr;
+    ButtonCallback callbackButtonPressed = nullptr;
 
     int encoderPinMode = INPUT;
     int buttonPinMode  = INPUT;