diff --git a/native/src/correction.cpp b/native/src/correction.cpp
index 0c56680..f6b7eb6 100644
--- a/native/src/correction.cpp
+++ b/native/src/correction.cpp
@@ -87,7 +87,7 @@
     int *const current = editDistanceTable + outputLength * (inputLength + 1);
     const int *const prev = editDistanceTable + (outputLength - 1) * (inputLength + 1);
     const int *const prevprev =
-            outputLength >= 2 ? editDistanceTable + (outputLength - 2) * (inputLength + 1) : NULL;
+            outputLength >= 2 ? editDistanceTable + (outputLength - 2) * (inputLength + 1) : 0;
     current[0] = outputLength;
     const uint32_t co = Dictionary::toBaseLowerCase(output[outputLength - 1]);
     const uint32_t prevCO =
diff --git a/native/src/proximity_info.cpp b/native/src/proximity_info.cpp
index 20fa18a..2f989e3 100644
--- a/native/src/proximity_info.cpp
+++ b/native/src/proximity_info.cpp
@@ -47,7 +47,7 @@
           HAS_TOUCH_POSITION_CORRECTION_DATA(keyCount > 0 && keyXCoordinates && keyYCoordinates
                   && keyWidths && keyHeights && keyCharCodes && sweetSpotCenterXs
                   && sweetSpotCenterYs && sweetSpotRadii),
-          mInputXCoordinates(NULL), mInputYCoordinates(NULL),
+          mInputXCoordinates(0), mInputYCoordinates(0),
           mTouchPositionCorrectionEnabled(false) {
     const int len = GRID_WIDTH * GRID_HEIGHT * MAX_PROXIMITY_CHARS_SIZE;
     mProximityCharsArray = new uint32_t[len];
diff --git a/native/src/proximity_info.h b/native/src/proximity_info.h
index 19b84cc..832db10 100644
--- a/native/src/proximity_info.h
+++ b/native/src/proximity_info.h
@@ -21,10 +21,6 @@
 
 #include "defines.h"
 
-#ifndef NULL
-#define NULL 0
-#endif
-
 namespace latinime {
 
 class Correction;
@@ -60,7 +56,7 @@
     bool existsCharInProximityAt(const int index, const int c) const;
     bool existsAdjacentProximityChars(const int index) const;
     ProximityType getMatchedProximityId(const int index, const unsigned short c,
-            const bool checkProximityChars, int *proximityIndex = NULL) const;
+            const bool checkProximityChars, int *proximityIndex = 0) const;
     int getNormalizedSquaredDistance(const int inputIndex, const int proximityIndex) const {
         return mNormalizedSquaredDistances[inputIndex * MAX_PROXIMITY_CHARS_SIZE + proximityIndex];
     }
diff --git a/native/src/unigram_dictionary.h b/native/src/unigram_dictionary.h
index ef9709a..4f4fef2 100644
--- a/native/src/unigram_dictionary.h
+++ b/native/src/unigram_dictionary.h
@@ -23,10 +23,6 @@
 #include "defines.h"
 #include "proximity_info.h"
 
-#ifndef NULL
-#define NULL 0
-#endif
-
 namespace latinime {
 
 class UnigramDictionary {