diff --git a/src/crypto/sha256_avx2.cpp b/src/crypto/sha256_avx2.cpp
--- a/src/crypto/sha256_avx2.cpp
+++ b/src/crypto/sha256_avx2.cpp
@@ -1,7 +1,7 @@
 #ifdef ENABLE_AVX2
 
+#include <cstdint>
 #include <immintrin.h>
-#include <stdint.h>
 
 #include "crypto/common.h"
 #include "crypto/sha256.h"
diff --git a/src/crypto/sha256_shani.cpp b/src/crypto/sha256_shani.cpp
--- a/src/crypto/sha256_shani.cpp
+++ b/src/crypto/sha256_shani.cpp
@@ -8,8 +8,8 @@
 
 #ifdef ENABLE_SHANI
 
+#include <cstdint>
 #include <immintrin.h>
-#include <stdint.h>
 
 #include <crypto/common.h>
 
diff --git a/src/crypto/sha256_sse4.cpp b/src/crypto/sha256_sse4.cpp
--- a/src/crypto/sha256_sse4.cpp
+++ b/src/crypto/sha256_sse4.cpp
@@ -5,8 +5,8 @@
 // This is a translation to GCC extended asm syntax from YASM code by Intel
 // (available at the bottom of this file).
 
-#include <stdint.h>
-#include <stdlib.h>
+#include <cstdint>
+#include <cstdlib>
 
 #if defined(__x86_64__) || defined(__amd64__)
 
diff --git a/src/crypto/sha256_sse41.cpp b/src/crypto/sha256_sse41.cpp
--- a/src/crypto/sha256_sse41.cpp
+++ b/src/crypto/sha256_sse41.cpp
@@ -1,7 +1,7 @@
 #ifdef ENABLE_SSE41
 
+#include <cstdint>
 #include <immintrin.h>
-#include <stdint.h>
 
 #include "crypto/common.h"
 #include "crypto/sha256.h"
diff --git a/src/fs.h b/src/fs.h
--- a/src/fs.h
+++ b/src/fs.h
@@ -5,7 +5,7 @@
 #ifndef BITCOIN_FS_H
 #define BITCOIN_FS_H
 
-#include <stdio.h>
+#include <cstdio>
 #include <string>
 
 #include <boost/filesystem.hpp>
diff --git a/src/httpserver.cpp b/src/httpserver.cpp
--- a/src/httpserver.cpp
+++ b/src/httpserver.cpp
@@ -15,7 +15,6 @@
 #include "util.h"
 #include "utilstrencodings.h"
 
-#include <signal.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 
@@ -34,6 +33,7 @@
 #endif
 #endif
 
+#include <csignal>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
diff --git a/src/init.cpp b/src/init.cpp
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -54,7 +54,7 @@
 #include <memory>
 
 #ifndef WIN32
-#include <signal.h>
+#include <csignal>
 #endif
 
 #include <boost/algorithm/string/classification.hpp>
diff --git a/src/net.cpp b/src/net.cpp
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -24,7 +24,7 @@
 #include "utilstrencodings.h"
 
 #ifdef WIN32
-#include <string.h>
+#include <cstring>
 #else
 #include <fcntl.h>
 #endif
diff --git a/src/seeder/main.cpp b/src/seeder/main.cpp
--- a/src/seeder/main.cpp
+++ b/src/seeder/main.cpp
@@ -9,11 +9,11 @@
 #include <algorithm>
 #include <atomic>
 #include <cinttypes>
+#include <csignal>
 #include <cstdio>
 #include <cstdlib>
 #include <getopt.h>
 #include <pthread.h>
-#include <signal.h>
 
 class CDnsSeedOpts {
 public:
diff --git a/src/test/univalue_tests.cpp b/src/test/univalue_tests.cpp
--- a/src/test/univalue_tests.cpp
+++ b/src/test/univalue_tests.cpp
@@ -4,8 +4,8 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "test/test_bitcoin.h"
+#include <cstdint>
 #include <map>
-#include <stdint.h>
 #include <string>
 #include <univalue.h>
 #include <vector>