diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_FCNTL_H.h b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_FCNTL_H.h
index 2b4e75b..6fa759e 100644
--- a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_FCNTL_H.h
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_FCNTL_H.h
@@ -6,10 +6,15 @@
 
 #undef HAVE_FCNTL_H
 
-#if defined(__linux__)   || \
-    defined(__FreeBSD__) || \
-    defined(__OpenBSD__) || \
-    defined(__NetBSD__)  || \
-    defined(BUILD2_AUTOCONF_MACOS)
+/* Note that there is <fcntl.h> on Windows (both MSVC and MinGW) though its
+ * declarations are not the same as on POSIX. But it does exist.
+ */
+
+#if defined(__linux__)              || \
+    defined(__FreeBSD__)            || \
+    defined(__OpenBSD__)            || \
+    defined(__NetBSD__)             || \
+    defined(BUILD2_AUTOCONF_MACOS)  || \
+    defined(_WIN32)
 #  define HAVE_FCNTL_H 1
 #endif
diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_IN6_ADDR.h b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_IN6_ADDR.h
index a9eb817..3094a2c 100644
--- a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_IN6_ADDR.h
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_IN6_ADDR.h
@@ -6,12 +6,13 @@
 
 #undef HAVE_STRUCT_IN6_ADDR
 
-/* Since Linux/glibc 2.1, OpenBSD 2.9, FreeBSD 3.5, NetBSD 1.5, and Mac OS X
+/* Since Linux/glibc 2.1, OpenBSD 2.9, FreeBSD 3.5, NetBSD 1.5, and Mac OS X, Windows
  */
-#if BUILD2_AUTOCONF_GLIBC_PREREQ(2, 1) || \
-    BUILD2_AUTOCONF_FREEBSD_PREREQ(3, 5)|| \
-    BUILD2_AUTOCONF_OPENBSD_PREREQ(200106) || \
-    BUILD2_AUTOCONF_NETBSD_PREREQ(1, 5) || \
-    defined(BUILD2_AUTOCONF_MACOS)
+#if BUILD2_AUTOCONF_GLIBC_PREREQ(2, 1)      || \
+    BUILD2_AUTOCONF_FREEBSD_PREREQ(3, 5)    || \
+    BUILD2_AUTOCONF_OPENBSD_PREREQ(200106)  || \
+    BUILD2_AUTOCONF_NETBSD_PREREQ(1, 5)     || \
+    defined(BUILD2_AUTOCONF_MACOS)          || \
+    defined(_WIN32)
 #  define HAVE_STRUCT_IN6_ADDR 1
 #endif
diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_IN6.h b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_IN6.h
index 02cb68f..8cb1510 100644
--- a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_IN6.h
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_IN6.h
@@ -6,11 +6,12 @@
 
 #undef HAVE_STRUCT_SOCKADDR_IN6
 
-/* Since OpenBSD ~4.2, FreeBSD ~7.0, NetBSD 2.1, Mac OS X 10.6
+/* Since OpenBSD ~4.2, FreeBSD ~7.0, NetBSD 2.1, Mac OS X 10.6, Windows
  */
 #if BUILD2_AUTOCONF_OPENBSD_PREREQ(200705)  || \
     BUILD2_AUTOCONF_FREEBSD_PREREQ(7, 0)    || \
     BUILD2_AUTOCONF_NETBSD_PREREQ(2, 1)     || \
-    BUILD2_AUTOCONF_MACOS_PREREQ(10, 6)
+    BUILD2_AUTOCONF_MACOS_PREREQ(10, 6)     || \
+    defined(_WIN32)
 #  define HAVE_STRUCT_SOCKADDR_IN6 1
 #endif
diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_STORAGE.h b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_STORAGE.h
index 8b0c26a..61b790e 100644
--- a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_STORAGE.h
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_STORAGE.h
@@ -6,12 +6,13 @@
 
 #undef HAVE_STRUCT_SOCKADDR_STORAGE
 
-/* Linux/glibc 2.1.1, Since 4.2BSD (~1983)
+/* Linux/glibc 2.1.1, Since 4.2BSD (~1983), Windows
  */
 #if BUILD2_AUTOCONF_GLIBC_PREREQ(2, 2)  || \
     defined(__FreeBSD__)                || \
     defined(__OpenBSD__)                || \
     defined(__NetBSD__)                 || \
-    defined(BUILD2_AUTOCONF_MACOS)
+    defined(BUILD2_AUTOCONF_MACOS)      || \
+    defined(_WIN32)
 #  define HAVE_STRUCT_SOCKADDR_STORAGE 1
 #endif
diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY.h b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY.h
index bbbe0fe..a01774e 100644
--- a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY.h
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY.h
@@ -6,7 +6,9 @@
 
 #undef HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY
 
-/* Since Linux/glibc 2.3, OpenBSD >=2.7, FreeBSD >=4.0, NetBSD >=1.5, Mac OS X 10.0
+/* Since Linux/glibc 2.3, OpenBSD >=2.7, FreeBSD >=4.0, NetBSD >=1.5, Mac OS X 10.0,
+ * Windows
+ *
  * NOTE: RFC2553 (<1999)    - defines __ss_len & __ss_family
  *       XNET draft (>1999) - defines ss_len & ss_family
  */
@@ -14,6 +16,7 @@
     BUILD2_AUTOCONF_OPENBSD_PREREQ(200015)  || \
     BUILD2_AUTOCONF_FREEBSD_PREREQ(4, 0)    || \
     BUILD2_AUTOCONF_NETBSD_PREREQ(1, 5)     || \
-    BUILD2_AUTOCONF_MACOS_PREREQ(10, 0)
+    BUILD2_AUTOCONF_MACOS_PREREQ(10, 0)     || \
+    defined(_WIN32)
 #  define HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY 1
 #endif
diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_SYS_STAT_H.h b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_SYS_STAT_H.h
index 755b9ef..20fdb04 100644
--- a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_SYS_STAT_H.h
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_SYS_STAT_H.h
@@ -7,10 +7,11 @@
 #undef HAVE_SYS_STAT_H
 /* Since 4.2BSD (~1983)
  */
-#if defined(__linux__)   || \
-    defined(__FreeBSD__) || \
-    defined(__OpenBSD__) || \
-    defined(__NetBSD__)  || \
-    defined(BUILD2_AUTOCONF_MACOS)
+#if defined(__linux__)              || \
+    defined(__FreeBSD__)            || \
+    defined(__OpenBSD__)            || \
+    defined(__NetBSD__)             || \
+    defined(BUILD2_AUTOCONF_MACOS)  || \
+    defined(_WIN32)
 #  define HAVE_SYS_STAT_H 1
 #endif