configure.ac |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/configure.ac b/configure.ac
index 39cc418..4892fda 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2285,6 +2285,18 @@ AM_CONDITIONAL(USE_MANUAL, test x"$USE_MANUAL" = x1)
 CURL_CHECK_LIB_ARES
 AM_CONDITIONAL(USE_EMBEDDED_ARES, test x$embedded_ares = xyes)
 
+AC_CHECK_HEADER(pthread.h,
+  [ AC_DEFINE(HAVE_PTHREAD_H, 1, [if you have <pthread.h>])
+    save_CFLAGS="$CFLAGS"
+    CFLAGS="$CFLAGS -pthread"
+    AC_CHECK_LIB(pthread, pthread_create,
+      [ AC_MSG_NOTICE([using POSIX threaded DNS lookup])
+        AC_DEFINE(USE_THREADS_POSIX, 1, [if you want POSIX threaded DNS lookup])
+        USE_THREADS_POSIX=1
+      ],
+      [ CFLAGS="$save_CFLAGS"])
+  ])
+
 dnl ************************************************************
 dnl disable verbose text strings
 dnl
@@ -2478,7 +2490,7 @@ fi
 if test "x$HAVE_LIBZ" = "x1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES libz"
 fi
-if test "x$USE_ARES" = "x1"; then
+if test "x$USE_ARES" = "x1" -o "x$USE_THREADS_POSIX" = "x1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES AsynchDNS"
 fi
 if test "x$IDN_ENABLED" = "x1"; then