new file mode 100644
--- /dev/null
+++ b/lib/check-version.c
@@ -0,0 +1,47 @@
+/* check-version.h --- Check version string compatibility.
+   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free
+   Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Simon Josefsson.  This interface is influenced by
+   gcry_check_version from Werner Koch's Libgcrypt.  Paul Eggert
+   suggested the use of strverscmp to simplify implementation. */
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <stddef.h>
+#include <strverscmp.h>
+
+/* Get specification. */
+#include "check_version.h"
+
+/* Check that the the version of the library (i.e., the CPP symbol
+ * VERSION) is at minimum the requested one in REQ_VERSION (typically
+ * found in a header file) and return the version string.  Return NULL
+ * if the condition is not satisfied.  If a NULL is passed to this
+ * function, no check is done, but the version string is simply
+ * returned.
+ */
+const char *
+check_version (const char *req_version)
+{
+  if (!req_version || strverscmp (req_version, VERSION) < 0)
+    return VERSION;
+
+  return NULL;
+}