diff --git a/configure.ac b/configure.ac
index be1b2fd..d1cdd2d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -56,6 +56,13 @@ AC_CHECK_LIB(nettle,main,,[AC_MSG_ERROR([
  and try again.
 ])])
 
+dnl make sure to set feature test macros to use symlink
+AH_VERBATIM([_POSIX_C_SOURCE],
+          [/* Make "extra" functions available such as symlink() */
+          #ifndef _POSIX_C_SOURCE
+          # define _POSIX_C_SOURCE 200112L
+          #endif])
+
 dnl test for some specific functions
 AC_CHECK_FUNC(stat,,AC_MSG_ERROR(oops! no stat ?!?))