diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index f09a3534628..4b5413f9e3b 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -211,6 +211,9 @@ Trunk (Unreleased)
     MAPREDUCE-6391. util/Timer.cc completely misunderstands _POSIX_CPUTIME
     (Alan Burlison via aw)
 
+    MAPREDUCE-6412. Make hadoop-mapreduce-client Native code -Wall-clean
+    (Alan Burlison via aw)
+
   BREAKDOWN OF MAPREDUCE-2841 (NATIVE TASK) SUBTASKS
 
     MAPREDUCE-5985. native-task: Fix build on macosx. Contributed by
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/Buffers.h b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/Buffers.h
index 13cd545a24f..4929426d9f8 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/Buffers.h
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/Buffers.h
@@ -349,31 +349,31 @@ public:
     return this->_capacity;
   }
 
-  int remain() {
+  uint32_t remain() {
     return _limit - _position;
   }
 
-  int limit() {
+  uint32_t limit() {
     return _limit;
   }
 
-  int advance(int positionOffset) {
+  uint32_t advance(int positionOffset) {
     _position += positionOffset;
     return _position;
   }
 
-  int position() {
+  uint32_t position() {
     return this->_position;
   }
 
-  void position(int newPos) {
+  void position(uint32_t newPos) {
     this->_position = newPos;
   }
 
-  void rewind(int newPos, int newLimit) {
+  void rewind(uint32_t newPos, uint32_t newLimit) {
     this->_position = newPos;
-    if (newLimit < 0 || newLimit > this->_capacity) {
-      THROW_EXCEPTION(IOException, "length smaller than zero or larger than input buffer capacity");
+    if (newLimit > this->_capacity) {
+      THROW_EXCEPTION(IOException, "length larger than input buffer capacity");
     }
     this->_limit = newLimit;
   }
@@ -474,11 +474,10 @@ public:
    * return the length of actually filled data.
    */
   uint32_t fill(const char * source, uint32_t maxSize) {
-    int remain = _size - _pos;
-    if (remain <= 0) {
+    if (_pos > _size) {
       return 0;
     }
-
+    uint32_t remain = _size - _pos;
     uint32_t length = (maxSize < remain) ? maxSize : remain;
     simple_memcpy(_buff + _pos, source, length);
     _pos += length;
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/MemoryBlock.cc b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/MemoryBlock.cc
index b3734a170b7..cd6872a9287 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/MemoryBlock.cc
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/MemoryBlock.cc
@@ -39,8 +39,8 @@ MemoryBlock::MemoryBlock(char * pos, uint32_t size)
     : _base(pos), _size(size), _position(0), _sorted(false) {
 }
 
-KVBuffer * MemoryBlock::getKVBuffer(int index) {
-  if (index < 0 || index >= _kvOffsets.size()) {
+KVBuffer * MemoryBlock::getKVBuffer(uint32_t index) {
+  if (index >= _kvOffsets.size()) {
     return NULL;
   }
   uint32_t offset = _kvOffsets.at(index);
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/MemoryBlock.h b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/MemoryBlock.h
index f85c3b61f1f..29f451839a9 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/MemoryBlock.h
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/lib/MemoryBlock.h
@@ -97,7 +97,7 @@ public:
     return _kvOffsets.size();
   }
 
-  KVBuffer * getKVBuffer(int index);
+  KVBuffer * getKVBuffer(uint32_t index);
 
   void sort(SortAlgorithm type, ComparatorPtr comparator);
 };
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/util/Random.cc b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/util/Random.cc
index 6266b1f0492..2747cd927f4 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/util/Random.cc
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/util/Random.cc
@@ -179,7 +179,7 @@ char * Words[] = {"diurnalness", "Homoiousian", "spiranthic", "tetragynian", "si
     "lithotresis", "minniebush", "zanyism", "eucalypteol", "sterilely", "unrealize", "unpatched",
     "hypochondriacism", "critically", "cheesecutter", };
 
-static size_t WordsCount = sizeof(Words) / sizeof(char *);
+static uint32_t WordsCount = sizeof(Words) / sizeof(char *);
 
 Random::Random() {
   setSeed(time(NULL) + clock() + RandomInitializeID++);
@@ -249,7 +249,7 @@ uint64_t Random::nextLog2(uint64_t range) {
 }
 
 uint64_t Random::nextLog10(uint64_t range) {
-  double range_r = log10(range);
+  double range_r = log10((double)range);
   double v = nextDouble() * range_r;
   return (uint64_t)pow(10, v);
 }
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/util/WritableUtils.cc b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/util/WritableUtils.cc
index 243668117b3..8ed8dd2f3f5 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/util/WritableUtils.cc
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/src/util/WritableUtils.cc
@@ -155,7 +155,8 @@ int64_t WritableUtils::ReadVLong(InputStream * stream) {
   }
   uint32_t len = DecodeVLongSize(buff);
   if (len > 1) {
-    if (stream->readFully(buff + 1, len - 1) != len - 1) {
+    len--;
+    if (stream->readFully(buff + 1, len) != (int32_t)len) {
       THROW_EXCEPTION(IOException, "ReadVLong reach EOF");
     }
   }
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/test/TestPrimitives.cc b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/test/TestPrimitives.cc
index b2051c7b32b..93732732a54 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/test/TestPrimitives.cc
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/native/test/TestPrimitives.cc
@@ -141,7 +141,7 @@ inline char * memchrbrf4(char * p, char ch, size_t len) {
       return p + i + 2;
     }
   }
-  for (; i < len; i++) {
+  for (; i < (ssize_t)len; i++) {
     if (p[i] == ch) {
       return p + i;
     }