diff --git a/MessagePackPacker.m b/MessagePackPacker.m
index 28af09b..f9957cc 100644
--- a/MessagePackPacker.m
+++ b/MessagePackPacker.m
@@ -72,7 +72,7 @@ + (void)packObject:(id)obj into:(msgpack_packer*)pk {
 		}
 	} else if ([obj isKindOfClass:[NSString class]]) {
 		const char *str = ((NSString*)obj).UTF8String;
-		int len = strlen(str);
+		size_t len = strlen(str);
 		msgpack_pack_raw(pk, len);
 		msgpack_pack_raw_body(pk, str, len);
 	} else if ([obj isKindOfClass:[NSNumber class]]) {
diff --git a/msgpack_src/msgpack/pack.h b/msgpack_src/msgpack/pack.h
index f86e929..6b356ce 100644
--- a/msgpack_src/msgpack/pack.h
+++ b/msgpack_src/msgpack/pack.h
@@ -86,9 +86,9 @@ static int msgpack_pack_nil(msgpack_packer* pk);
 static int msgpack_pack_true(msgpack_packer* pk);
 static int msgpack_pack_false(msgpack_packer* pk);
 
-static int msgpack_pack_array(msgpack_packer* pk, unsigned int n);
+static int msgpack_pack_array(msgpack_packer* pk, size_t n);
 
-static int msgpack_pack_map(msgpack_packer* pk, unsigned int n);
+static int msgpack_pack_map(msgpack_packer* pk, size_t n);
 
 static int msgpack_pack_raw(msgpack_packer* pk, size_t l);
 static int msgpack_pack_raw_body(msgpack_packer* pk, const void* b, size_t l);
diff --git a/msgpack_src/msgpack/pack_template.h b/msgpack_src/msgpack/pack_template.h
index da54c36..c72c933 100644
--- a/msgpack_src/msgpack/pack_template.h
+++ b/msgpack_src/msgpack/pack_template.h
@@ -683,7 +683,7 @@ msgpack_pack_inline_func(_false)(msgpack_pack_user x)
  * Array
  */
 
-msgpack_pack_inline_func(_array)(msgpack_pack_user x, unsigned int n)
+msgpack_pack_inline_func(_array)(msgpack_pack_user x, size_t n)
 {
 	if(n < 16) {
 		unsigned char d = 0x90 | n;
@@ -704,7 +704,7 @@ msgpack_pack_inline_func(_array)(msgpack_pack_user x, unsigned int n)
  * Map
  */
 
-msgpack_pack_inline_func(_map)(msgpack_pack_user x, unsigned int n)
+msgpack_pack_inline_func(_map)(msgpack_pack_user x, size_t n)
 {
 	if(n < 16) {
 		unsigned char d = 0x80 | n;
@@ -743,7 +743,12 @@ msgpack_pack_inline_func(_raw)(msgpack_pack_user x, size_t l)
 
 msgpack_pack_inline_func(_raw_body)(msgpack_pack_user x, const void* b, size_t l)
 {
-	msgpack_pack_append_buffer(x, (const unsigned char*)b, l);
+    if(l < 65536) {
+        msgpack_pack_append_buffer(x, (const unsigned char*)b, (uint16_t)l);
+    } else {
+        msgpack_pack_append_buffer(x, (const unsigned char*)b, (uint32_t)l);
+    }
+	
 }
 
 #undef msgpack_pack_inline_func