diff --git a/include/platform/messagepool.h b/include/platform/messagepool.h
index 418018160..317a2336a 100644
--- a/include/platform/messagepool.h
+++ b/include/platform/messagepool.h
@@ -65,11 +65,11 @@ extern "C" {
 /**
  * Initialize the platform implemented message pool.
  *
- * @param[in] aMinNumFreeBuffers   An int containing the minimum number of free buffers desired by OpenThread.
+ * @param[in] aMinNumFreeBuffers   An uint16 containing the minimum number of free buffers desired by OpenThread.
  * @param[in] aBufferSize          The size in bytes of a Buffer object.
  *
  */
-void otPlatMessagePoolInit(int aMinNumFreeBuffers, size_t aBufferSize);
+void otPlatMessagePoolInit(uint16_t aMinNumFreeBuffers, size_t aBufferSize);
 
 /**
  * Allocate a buffer from the platform managed buffer pool.
@@ -93,7 +93,7 @@ void otPlatMessagePoolFree(struct BufferHeader *aBuffer);
  * @returns The number of buffers currently free and available to OpenThread.
  *
  */
-int otPlatMessagePoolNumFreeBuffers(void);
+uint16_t otPlatMessagePoolNumFreeBuffers(void);
 
 #ifdef __cplusplus
 }  // extern "C"
diff --git a/src/core/common/message.cpp b/src/core/common/message.cpp
index 1f2232957..eaf46fe83 100644
--- a/src/core/common/message.cpp
+++ b/src/core/common/message.cpp
@@ -52,7 +52,7 @@ MessagePool::MessagePool(void) :
 
     mFreeBuffers = mBuffers;
 
-    for (int i = 0; i < kNumBuffers - 1; i++)
+    for (uint16_t i = 0; i < kNumBuffers - 1; i++)
     {
         mBuffers[i].SetNextBuffer(&mBuffers[i + 1]);
     }
@@ -148,7 +148,7 @@ ThreadError MessagePool::FreeBuffers(Buffer *aBuffer)
 
 ThreadError MessagePool::ReclaimBuffers(int aNumBuffers)
 {
-    int numFreeBuffers;
+    uint16_t numFreeBuffers;
 
 #if OPENTHREAD_CONFIG_PLATFORM_MESSAGE_MANAGEMENT
     numFreeBuffers = otPlatMessagePoolNumFreeBuffers();
@@ -156,7 +156,17 @@ ThreadError MessagePool::ReclaimBuffers(int aNumBuffers)
     numFreeBuffers = mNumFreeBuffers;
 #endif
 
-    return (aNumBuffers <= numFreeBuffers) ? kThreadError_None : kThreadError_NoBufs;
+    //First comparison is to get around issues with comparing
+    //signed and unsigned numbers, if aNumBuffers is negative then
+    //the second comparison wont be attempted.
+    if (aNumBuffers < 0 || aNumBuffers <= numFreeBuffers)
+    {
+        return kThreadError_None;
+    }
+    else
+    {
+        return kThreadError_NoBufs;
+    }
 }
 
 Message *MessagePool::Iterator::Next(void) const
diff --git a/src/core/common/message.hpp b/src/core/common/message.hpp
index f6dc879bf..2970e6906 100644
--- a/src/core/common/message.hpp
+++ b/src/core/common/message.hpp
@@ -1102,9 +1102,9 @@ public:
      *
      */
 #if OPENTHREAD_CONFIG_PLATFORM_MESSAGE_MANAGEMENT
-    uint16_t GetFreeBufferCount(void) const { return static_cast<uint16_t>(otPlatMessagePoolNumFreeBuffers()); }
+    uint16_t GetFreeBufferCount(void) const { return otPlatMessagePoolNumFreeBuffers(); }
 #else
-    uint16_t GetFreeBufferCount(void) const { return static_cast<uint16_t>(mNumFreeBuffers); }
+    uint16_t GetFreeBufferCount(void) const { return mNumFreeBuffers; }
 #endif
 
 private:
@@ -1119,9 +1119,9 @@ private:
     PriorityQueue *GetAllMessagesQueue(void) { return &mAllQueue; }
 
 #if OPENTHREAD_CONFIG_PLATFORM_MESSAGE_MANAGEMENT == 0
-    int mNumFreeBuffers;
-    Buffer mBuffers[kNumBuffers];
-    Buffer *mFreeBuffers;
+    uint16_t mNumFreeBuffers;
+    Buffer   mBuffers[kNumBuffers];
+    Buffer   *mFreeBuffers;
 #endif
     PriorityQueue mAllQueue;
 };