diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_DECL_CTL_KERN.h b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_DECL_CTL_KERN.h
new file mode 100644
index 0000000..d385029
--- /dev/null
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_DECL_CTL_KERN.h
@@ -0,0 +1,18 @@
+// HAVE_DECL_CTL_KERN : BUILD2_AUTOCONF_LIBC_VERSION
+
+#ifndef BUILD2_AUTOCONF_LIBC_VERSION
+#  error BUILD2_AUTOCONF_LIBC_VERSION appears to be conditionally included
+#endif
+
+#undef HAVE_DECL_CTL_KERN
+/* Since 4.4BSD (OpenBSD 2.1-6.2, FreeBSD, NetBSD, Mac OS X 10.7),
+ * <= glibc 2.31.
+ * NOTE: Appears to have been available parallel to sysctl()
+ */
+#if (BUILD2_AUTOCONF_OPENBSD_PREREQ(199706) && !BUILD2_AUTOCONF_OPENBSD_PREREQ(201804)) || \
+    BUILD2_AUTOCONF_FREEBSD_PREREQ(2, 3)   || \
+    BUILD2_AUTOCONF_NETBSD_PREREQ(2, 0)    || \
+    BUILD2_AUTOCONF_MACOS_PREREQ(10, 7)    || \
+    !BUILD2_AUTOCONF_GLIBC_PREREQ(2, 32)
+#  define HAVE_DECL_CTL_KERN 1
+#endif
diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_DECL_KERN_ARND.h b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_DECL_KERN_ARND.h
new file mode 100644
index 0000000..9c70547
--- /dev/null
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_DECL_KERN_ARND.h
@@ -0,0 +1,13 @@
+// HAVE_DECL_KERN_ARND : BUILD2_AUTOCONF_LIBC_VERSION
+
+#ifndef BUILD2_AUTOCONF_LIBC_VERSION
+#  error BUILD2_AUTOCONF_LIBC_VERSION appears to be conditionally included
+#endif
+
+#undef HAVE_DECL_KERN_ARND
+/* OpenBSD 2.6-6.0.
+ * NOTE: Only mentioned in OpenBSD manual.
+ */
+#if (BUILD2_AUTOCONF_OPENBSD_PREREQ(199912) && !BUILD2_AUTOCONF_OPENBSD_PREREQ(201609))
+#  define HAVE_DECL_KERN_ARND 1
+#endif