diff --git a/TunDevice.cpp b/TunDevice.cpp
index 2767811..7cd6ea4 100644
--- a/TunDevice.cpp
+++ b/TunDevice.cpp
@@ -5,8 +5,8 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <errno.h>
-#include <cstdlib>
-#include <cstring>
+#include <stdlib.h>
+#include <string.h>
 
 #include "TunDevice.hpp"
 
diff --git a/UdpVpnClient.cpp b/UdpVpnClient.cpp
index 4f452ea..ff3c357 100644
--- a/UdpVpnClient.cpp
+++ b/UdpVpnClient.cpp
@@ -1,4 +1,4 @@
-#include <cstring>
+#include <string.h>
 
 #include "UdpVpnClient.hpp"
 #include "ip_header.hpp"
diff --git a/UdpVpnServer.cpp b/UdpVpnServer.cpp
index 8592cee..3e58966 100644
--- a/UdpVpnServer.cpp
+++ b/UdpVpnServer.cpp
@@ -1,4 +1,4 @@
-#include <cstring>
+#include <string.h>
 
 #include "UdpVpnServer.hpp"
 #include "ip_header.hpp"
diff --git a/UdpVpnServer.hpp b/UdpVpnServer.hpp
index 841070c..2eccaae 100644
--- a/UdpVpnServer.hpp
+++ b/UdpVpnServer.hpp
@@ -1,6 +1,5 @@
 #pragma once
 
-#include <unordered_map>
 #include <memory>
 
 #include "UdpVpn.hpp"
diff --git a/VpnPacket.cpp b/VpnPacket.cpp
index 1c3a0e1..651957a 100644
--- a/VpnPacket.cpp
+++ b/VpnPacket.cpp
@@ -1,7 +1,7 @@
 #include "VpnPacket.hpp"
 #include "VpnPeer.hpp"
 
-#include <cstring>
+#include <string.h>
 
 const size_t VpnPacket::VPN_HEADER_BYTES = 8;
 const size_t VpnControlPacket::TLV_HEADER_BYTES = 3;
diff --git a/VpnPacket.hpp b/VpnPacket.hpp
index ccb0bae..0ebaee1 100644
--- a/VpnPacket.hpp
+++ b/VpnPacket.hpp
@@ -2,7 +2,7 @@
 
 /** A packet to be transmitted or received over the VPN socket */
 
-#include <cstdlib>
+#include <stdlib.h>
 #include <memory>
 
 #include "ip_header.hpp"
diff --git a/VpnPeer.cpp b/VpnPeer.cpp
index df632e2..a7b322a 100644
--- a/VpnPeer.cpp
+++ b/VpnPeer.cpp
@@ -1,9 +1,8 @@
 #include "UdpVpn.hpp"
 #include "congestion_control.hpp"
 
-#include <cstdint>
-#include <cstring>
-#include <functional>
+#include <stdint.h>
+#include <string.h>
 
 const double RTTLogger::EXP_AVG_FACTOR = 0.75;
 const unsigned int RTTLogger::BASE_UPDATE_DELAY = 1000; // ms
diff --git a/ip_header.cpp b/ip_header.cpp
index 8e0dfd6..15f69f9 100644
--- a/ip_header.cpp
+++ b/ip_header.cpp
@@ -1,4 +1,4 @@
-#include <cstring>
+#include <string.h>
 
 #include "ip_header.hpp"
 #include "util.hpp"
diff --git a/main.cpp b/main.cpp
index f17a034..02c91c0 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,5 +1,5 @@
-#include <cstdio>
-#include <cstdlib>
+#include <stdio.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include <arpa/inet.h>
 #include <signal.h>
diff --git a/util.cpp b/util.cpp
index 36fd440..1ed667a 100644
--- a/util.cpp
+++ b/util.cpp
@@ -1,4 +1,4 @@
-#include <cstdio>
+#include <stdio.h>
 #include <string.h>
 #include <stdarg.h>
 #include <arpa/inet.h>