diff --git a/unix/m4/isc-posix.m4 b/unix/m4/isc-posix.m4
new file mode 100644
index 0000000..74dc8f2
--- /dev/null
+++ b/unix/m4/isc-posix.m4
@@ -0,0 +1,24 @@
+# isc-posix.m4 serial 2 (gettext-0.11.2)
+dnl Copyright (C) 1995-2002 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+# This file is not needed with autoconf-2.53 and newer.  Remove it in 2005.
+
+# This test replaces the one in autoconf.
+# Currently this macro should have the same name as the autoconf macro
+# because gettext's gettext.m4 (distributed in the automake package)
+# still uses it.  Otherwise, the use in gettext.m4 makes autoheader
+# give these diagnostics:
+#   configure.in:556: AC_TRY_COMPILE was called before AC_ISC_POSIX
+#   configure.in:556: AC_TRY_RUN was called before AC_ISC_POSIX
+
+undefine([AC_ISC_POSIX])
+
+AC_DEFUN([AC_ISC_POSIX],
+  [
+    dnl This test replaces the obsolescent AC_ISC_POSIX kludge.
+    AC_CHECK_LIB(cposix, strerror, [LIBS="$LIBS -lcposix"])
+  ]
+)