diff --git a/winsup/cygwin/fhandler_procnet.cc b/winsup/cygwin/fhandler_procnet.cc
index a81ddecf9..452f33c57 100644
--- a/winsup/cygwin/fhandler_procnet.cc
+++ b/winsup/cygwin/fhandler_procnet.cc
@@ -16,21 +16,15 @@ details. */
 #undef u_long
 #define u_long __ms_u_long
 #endif
-#include <ws2tcpip.h>
-#include <iphlpapi.h>
+#include <w32api/ws2tcpip.h>
+#include <w32api/iphlpapi.h>
+#include <asm/byteorder.h>
+#include <stdio.h>
 #include "cygerrno.h"
-#include "security.h"
 #include "path.h"
 #include "fhandler.h"
 #include "fhandler_virtual.h"
 #include "dtable.h"
-#include "cygheap.h"
-#include <asm/byteorder.h>
-
-#define _COMPILING_NEWLIB
-#include <dirent.h>
-#include <stdio.h>
-#include <stdlib.h>
 
 bool get_adapters_addresses (PIP_ADAPTER_ADDRESSES *pa0, ULONG family);
 
diff --git a/winsup/cygwin/fhandler_socket.cc b/winsup/cygwin/fhandler_socket.cc
index 5f00e6946..4ef4a755b 100644
--- a/winsup/cygwin/fhandler_socket.cc
+++ b/winsup/cygwin/fhandler_socket.cc
@@ -6,48 +6,18 @@
    Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
    details. */
 
-#define  __INSIDE_CYGWIN_NET__
-#define USE_SYS_TYPES_FD_SET
-
 #include "winsup.h"
-#ifdef __x86_64__
-/* 2014-04-24: Current Mingw headers define sockaddr_in6 using u_long (8 byte)
-   because a redefinition for LP64 systems is missing.  This leads to a wrong
-   definition and size of sockaddr_in6 when building with winsock headers.
-   This definition is also required to use the right u_long type in subsequent
-   function calls. */
-#undef u_long
-#define u_long __ms_u_long
-#endif
-#include <ntsecapi.h>
-#include <ws2tcpip.h>
-#include <mswsock.h>
-#include <iphlpapi.h>
-#include "cygerrno.h"
-#include "security.h"
-#include "path.h"
-#include "fhandler.h"
-#include "dtable.h"
-#include "cygheap.h"
+#include <sys/socket.h>
 #include <asm/byteorder.h>
-#include "cygwin/version.h"
-#include "perprocess.h"
-#include "shared_info.h"
-#include "sigproc.h"
-#include "wininfo.h"
 #include <unistd.h>
 #include <sys/param.h>
 #include <sys/statvfs.h>
 #include <cygwin/acl.h>
-#include "cygtls.h"
-#include <sys/un.h>
-#include "ntdll.h"
-#include "miscfuncs.h"
+#include "cygerrno.h"
+#include "path.h"
+#include "fhandler.h"
 #include "tls_pbuf.h"
 
-#define ASYNC_MASK (FD_READ|FD_WRITE|FD_OOB|FD_ACCEPT|FD_CONNECT)
-#define EVENT_MASK (FD_READ|FD_WRITE|FD_OOB|FD_ACCEPT|FD_CONNECT|FD_CLOSE)
-
 extern "C" {
   int sscanf (const char *, const char *, ...);
 } /* End of "C" section */
diff --git a/winsup/cygwin/fhandler_socket_inet.cc b/winsup/cygwin/fhandler_socket_inet.cc
index b0dc6581c..a3aeccc82 100644
--- a/winsup/cygwin/fhandler_socket_inet.cc
+++ b/winsup/cygwin/fhandler_socket_inet.cc
@@ -21,31 +21,21 @@
 #undef u_long
 #define u_long __ms_u_long
 #endif
-#include <ntsecapi.h>
-#include <ws2tcpip.h>
-#include <mswsock.h>
-#include <iphlpapi.h>
+#include <w32api/ws2tcpip.h>
+#include <w32api/mswsock.h>
+#include <unistd.h>
+#include <asm/byteorder.h>
+#include <sys/socket.h>
+#include <sys/param.h>
+#include <sys/statvfs.h>
+#include <cygwin/acl.h>
 #include "cygerrno.h"
-#include "security.h"
 #include "path.h"
 #include "fhandler.h"
 #include "dtable.h"
 #include "cygheap.h"
-#include <asm/byteorder.h>
-#include "cygwin/version.h"
-#include "perprocess.h"
 #include "shared_info.h"
-#include "sigproc.h"
 #include "wininfo.h"
-#include <unistd.h>
-#include <sys/param.h>
-#include <sys/statvfs.h>
-#include <cygwin/acl.h>
-#include "cygtls.h"
-#include <sys/un.h>
-#include "ntdll.h"
-#include "miscfuncs.h"
-#include "tls_pbuf.h"
 
 #define ASYNC_MASK (FD_READ|FD_WRITE|FD_OOB|FD_ACCEPT|FD_CONNECT)
 #define EVENT_MASK (FD_READ|FD_WRITE|FD_OOB|FD_ACCEPT|FD_CONNECT|FD_CLOSE)
diff --git a/winsup/cygwin/fhandler_socket_local.cc b/winsup/cygwin/fhandler_socket_local.cc
index ad2df6568..844cb9d11 100644
--- a/winsup/cygwin/fhandler_socket_local.cc
+++ b/winsup/cygwin/fhandler_socket_local.cc
@@ -21,31 +21,23 @@
 #undef u_long
 #define u_long __ms_u_long
 #endif
-#include <ntsecapi.h>
-#include <ws2tcpip.h>
-#include <mswsock.h>
-#include <iphlpapi.h>
+#include <w32api/ntsecapi.h>
+#include <w32api/ws2tcpip.h>
+#include <w32api/mswsock.h>
+#include <unistd.h>
+#include <asm/byteorder.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/param.h>
+#include <sys/statvfs.h>
+#include <cygwin/acl.h>
 #include "cygerrno.h"
-#include "security.h"
 #include "path.h"
 #include "fhandler.h"
 #include "dtable.h"
 #include "cygheap.h"
-#include <asm/byteorder.h>
-#include "cygwin/version.h"
-#include "perprocess.h"
-#include "shared_info.h"
-#include "sigproc.h"
 #include "wininfo.h"
-#include <unistd.h>
-#include <sys/param.h>
-#include <sys/statvfs.h>
-#include <cygwin/acl.h>
-#include "cygtls.h"
-#include <sys/un.h>
 #include "ntdll.h"
-#include "miscfuncs.h"
-#include "tls_pbuf.h"
 
 extern "C" {
   int sscanf (const char *, const char *, ...);
diff --git a/winsup/cygwin/fhandler_socket_unix.cc b/winsup/cygwin/fhandler_socket_unix.cc
index c539c00a1..ec4170ff5 100644
--- a/winsup/cygwin/fhandler_socket_unix.cc
+++ b/winsup/cygwin/fhandler_socket_unix.cc
@@ -9,25 +9,20 @@
    details. */
 
 #include "winsup.h"
-#include <ntsecapi.h>
-#include "cygerrno.h"
-#include "security.h"
-#include "path.h"
-#include "fhandler.h"
-#include "dtable.h"
-#include "cygheap.h"
+#include <w32api/winioctl.h>
 #include <asm/byteorder.h>
-#include "cygwin/version.h"
-#include "perprocess.h"
-#include "shared_info.h"
-#include "sigproc.h"
-#include "wininfo.h"
 #include <unistd.h>
+#include <sys/socket.h>
+#include <sys/un.h>
 #include <sys/param.h>
 #include <sys/statvfs.h>
 #include <cygwin/acl.h>
-#include "cygtls.h"
-#include <sys/un.h>
+#include "cygerrno.h"
+#include "path.h"
+#include "fhandler.h"
+#include "dtable.h"
+#include "hires.h"
+#include "shared_info.h"
 #include "ntdll.h"
 #include "miscfuncs.h"
 #include "tls_pbuf.h"
diff --git a/winsup/cygwin/include/sys/un.h b/winsup/cygwin/include/sys/un.h
index fa5ce278f..53be57b38 100644
--- a/winsup/cygwin/include/sys/un.h
+++ b/winsup/cygwin/include/sys/un.h
@@ -9,14 +9,15 @@ details. */
 #ifndef _SYS_UN_H
 #define _SYS_UN_H
 
+#include <sys/types.h>
 #include <string.h>		/* for strlen */
-#include <cygwin/socket.h>
+
 
 /* POSIX requires only at least 100 bytes */
 #define UNIX_PATH_MAX   108
 
 struct sockaddr_un {
-  sa_family_t	 sun_family;              /* address family AF_LOCAL/AF_UNIX */
+  __sa_family_t	 sun_family;              /* address family AF_LOCAL/AF_UNIX */
   char	         sun_path[UNIX_PATH_MAX]; /* 108 bytes of socket address     */
 };
 
diff --git a/winsup/cygwin/net.cc b/winsup/cygwin/net.cc
index 25f94d684..38a53f815 100644
--- a/winsup/cygwin/net.cc
+++ b/winsup/cygwin/net.cc
@@ -19,35 +19,21 @@ details. */
 #undef u_long
 #define u_long __ms_u_long
 #endif
-#include <ws2tcpip.h>
-#include <mswsock.h>
-#include <iphlpapi.h>
-#include "miscfuncs.h"
-#include <ctype.h>
-#include <wchar.h>
-#include <stdlib.h>
+#include <w32api/ws2tcpip.h>
+#include <w32api/mswsock.h>
+#include <w32api/iphlpapi.h>
 #define gethostname cygwin_gethostname
 #include <unistd.h>
 #undef gethostname
+#include <ifaddrs.h>
 #include <netdb.h>
-#include <cygwin/in.h>
 #include <asm/byteorder.h>
-#include <assert.h>
-#include "cygerrno.h"
-#include "security.h"
-#include "cygwin/version.h"
 #include "shared_info.h"
-#include "perprocess.h"
 #include "path.h"
 #include "fhandler.h"
 #include "dtable.h"
 #include "cygheap.h"
-#include "sigproc.h"
-#include "registry.h"
-#include "cygtls.h"
-#include "ifaddrs.h"
 #include "tls_pbuf.h"
-#include "ntdll.h"
 
 /* Unfortunately defined in Windows header files and arpa/nameser_compat.h. */
 #undef NOERROR
@@ -455,8 +441,6 @@ dup_ent (unionent *&dst, unionent *src, unionent::struct_type type)
 	      dp += DWORD_round (src->h_len);
 	    }
 	}
-      /* Sanity check that we did our bookkeeping correctly. */
-      assert ((dp - (char *) dst) == sz);
     }
   debug_printf ("duped %sent \"%s\", %p", entnames[type], dst ? dst->name : "<null!>", dst);
   return dst;
diff --git a/winsup/cygwin/syslog.cc b/winsup/cygwin/syslog.cc
index 2f4e5e8c0..e753b60dd 100644
--- a/winsup/cygwin/syslog.cc
+++ b/winsup/cygwin/syslog.cc
@@ -15,6 +15,7 @@ details. */
 #include <stdio.h>
 #include <syslog.h>
 #include <unistd.h>
+#include <sys/socket.h>
 #include <sys/un.h>
 #include "cygerrno.h"
 #include "security.h"