diff --git a/cf/pthreads.m4 b/cf/pthreads.m4
new file mode 100644
index 000000000..aa3944453
--- /dev/null
+++ b/cf/pthreads.m4
@@ -0,0 +1,49 @@
+dnl $Id$
+
+AC_DEFUN(KRB_PTHREADS, [
+AC_MSG_CHECKING(if compiling threadsafe libraries)
+
+if test "$PTHREADS_LDFLAGS" = "" ; then
+    PTHREADS_LDFLAGS="-pthread"
+fi
+
+AC_ARG_ENABLE(pthread-support,
+	AC_HELP_STRING([--enable-pthread-support],
+			[if you want thread safe libraries]),
+	[],[enable_pthread_support=maybe])
+if test "$enable_pthread_support" = maybe; then
+case "$host" in 
+*-*-solaris2*)
+	enable_pthread_support=yes
+	;;
+*-*-netbsd*)
+	enable_pthread_support="if running netbsd 1.6T or newer"
+	dnl heim_threads.h knows this
+	;;
+*-*-freebsd5*)
+	enable_pthread_support=yes
+	;;
+*-*-linux2[4-9]*)
+	enable_pthread_support=yes
+	;;
+*-*-aix*)
+	enable_pthread_support=yes
+	;;
+*)
+	enable_pthread_support=no
+	;;
+esac
+fi
+if test "$enable_pthread_support" = no; then
+    AC_DEFINE(ENABLE_PTHREAD_SUPPORT, 1,
+	[Define if you want have a thread safe libraries])
+else
+  PTHREADS_CFLAGS=""
+  PTHREADS_LDFLAGS=""
+fi
+
+AC_SUBST(PTHREADS_CFLAGS)
+AC_SUBST(PTHREADS_LDFLAGS)
+
+AC_MSG_RESULT($enable_pthread_support)
+])