diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_UMASK.h b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_UMASK.h
new file mode 100644
index 0000000..c064baf
--- /dev/null
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_UMASK.h
@@ -0,0 +1,17 @@
+// HAVE_UMASK : BUILD2_AUTOCONF_LIBC_VERSION
+
+#ifndef BUILD2_AUTOCONF_LIBC_VERSION
+#  error BUILD2_AUTOCONF_LIBC_VERSION appears to be conditionally included
+#endif
+
+#undef HAVE_UMASK
+
+/*  Since glibc 2.1, FreeBSD 1.0, OpenBSD 2.0, NetBSD 1.0 and MacOS
+ */
+#if BUILD2_AUTOCONF_GLIBC_PREREQ(2, 1)    || \
+    BUILD2_AUTOCONF_FREEBSD_PREREQ(1, 0)  || \
+    BUILD2_AUTOCONF_OPENBSD_PREREQ(199610) || \
+    BUILD2_AUTOCONF_NETBSD_PREREQ(1, 0) || \
+    defined(BUILD2_AUTOCONF_MACOS)
+#  define HAVE_UMASK 1
+#endif