diff --git a/BitcoinUtil.cpp b/BitcoinUtil.cpp
index 87707f476..44beac43b 100644
--- a/BitcoinUtil.cpp
+++ b/BitcoinUtil.cpp
@@ -1,7 +1,7 @@
 #include "BitcoinUtil.h"
-#include <stdarg.h>
+#include <cstdarg>
 #include <openssl/rand.h>
-#include <time.h>
+#include <ctime>
 
 #if defined(WIN32) || defined(WIN64)
 #include <windows.h>
diff --git a/CallRPC.cpp b/CallRPC.cpp
index 1e0b26707..6094a5bfb 100644
--- a/CallRPC.cpp
+++ b/CallRPC.cpp
@@ -1,7 +1,7 @@
 
 
 #include <iostream>
-#include <stdlib.h>
+#include <cstdlib>
 
 #include <boost/asio.hpp>
 #include <boost/iostreams/concepts.hpp>
diff --git a/NewcoinAddress.cpp b/NewcoinAddress.cpp
index 01b203648..bb014da6e 100644
--- a/NewcoinAddress.cpp
+++ b/NewcoinAddress.cpp
@@ -1,7 +1,7 @@
 #include "NewcoinAddress.h"
 #include "Config.h"
 #include "BitcoinUtil.h"
-#include <assert.h>
+#include <cassert>
 
 
 bool NewcoinAddress::SetHash160(const uint160& hash160)
diff --git a/Serializer.cpp b/Serializer.cpp
index b487df691..03deb0136 100644
--- a/Serializer.cpp
+++ b/Serializer.cpp
@@ -1,6 +1,6 @@
 #include "Serializer.h"
 #include "key.h"
-#include <assert.h>
+#include <cassert>
 #include <openssl/ripemd.h>
 #include <openssl/sha.h>
 
diff --git a/uint256.h b/uint256.h
index 4077c5e59..d4b75ea7e 100644
--- a/uint256.h
+++ b/uint256.h
@@ -6,11 +6,11 @@
 #define NEWCOIN_UINT256_H
 
 
-#include <limits.h>
+#include <climits>
 #include <string>
 #include <vector>
-#include <stdio.h>
-#include <string.h>
+#include <cstdio>
+#include <cstring>
 
 #include "types.h"