diff --git a/include/dmlc/io.h b/include/dmlc/io.h
index f808094c1..1b7d70498 100644
--- a/include/dmlc/io.h
+++ b/include/dmlc/io.h
@@ -300,7 +300,7 @@ class istream : public std::basic_istream<char> {
 // implementations of inline functions
 template<typename T>
 inline void Stream::Write(const std::vector<T> &vec) {
-  size_t sz = vec.size();
+  uint64_t sz = static_cast<uint64_t>(vec.size());
   this->Write(&sz, sizeof(sz));
   if (sz != 0) {
     this->Write(&vec[0], sizeof(T) * sz);
@@ -308,25 +308,25 @@ inline void Stream::Write(const std::vector<T> &vec) {
 }
 template<typename T>
 inline bool Stream::Read(std::vector<T> *out_vec) {
-  size_t sz;
+  uint64_t sz;
   if (this->Read(&sz, sizeof(sz)) == 0) return false;
-  out_vec->resize(sz);
+  out_vec->resize(static_cast<size_t>(sz));
   if (sz != 0) {
     if (this->Read(&(*out_vec)[0], sizeof(T) * sz) == 0) return false;
   }
   return true;
 }
 inline void Stream::Write(const std::string &str) {
-  size_t sz = str.length();
+  uint64_t sz = static_cast<uint64_t>(str.length());
   this->Write(&sz, sizeof(sz));
   if (sz != 0) {
     this->Write(&str[0], sizeof(char) * sz);
   }
 }
 inline bool Stream::Read(std::string *out_str) {
-  size_t sz;
+  uint64_t sz;
   if (this->Read(&sz, sizeof(sz)) == 0) return false;
-  out_str->resize(sz);
+  out_str->resize(static_cast<size_t>(sz));
   if (sz != 0) {
     if (this->Read(&(*out_str)[0], sizeof(char) * sz) == 0) {
       return false;
diff --git a/include/rabit/rabit-inl.h b/include/rabit/rabit-inl.h
index 97c43767d..3d1ec59a8 100644
--- a/include/rabit/rabit-inl.h
+++ b/include/rabit/rabit-inl.h
@@ -174,6 +174,7 @@ inline void TrackerPrintf(const char *fmt, ...) {
   va_start(args, fmt);
   vsnprintf(&msg[0], kPrintBuffer, fmt, args);
   va_end(args);
+  msg.resize(strlen(msg.c_str()));
   TrackerPrint(msg);
 }
 #endif
diff --git a/include/rabit/utils.h b/include/rabit/utils.h
index aae3c6ab4..0f48fa0fa 100644
--- a/include/rabit/utils.h
+++ b/include/rabit/utils.h
@@ -43,10 +43,10 @@ extern "C" {
 
 #ifdef _MSC_VER
 typedef unsigned char uint8_t;
-typedef unsigned short int uint16_t;
-typedef unsigned int uint32_t;
-typedef unsigned long uint64_t;
-typedef long int64_t;
+typedef unsigned __int16 uint16_t;
+typedef unsigned __int32 uint32_t;
+typedef unsigned __int64 uint64_t;
+typedef __int64 int64_t;
 #else
 #include <inttypes.h>
 #endif