diff --git a/moo/configure b/moo/configure
index 50e7c82..3ee3c21 100755
--- a/moo/configure
+++ b/moo/configure
@@ -19654,6 +19654,17 @@ _ACEOF
 fi
 done
 
+for ac_func in accept4
+do :
+  ac_fn_c_check_func "$LINENO" "accept4" "ac_cv_func_accept4"
+if test "x$ac_cv_func_accept4" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_ACCEPT4 1
+_ACEOF
+
+fi
+done
+
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for dcNewCallVM in -ldyncall_s" >&5
 $as_echo_n "checking for dcNewCallVM in -ldyncall_s... " >&6; }
diff --git a/moo/configure.ac b/moo/configure.ac
index 98d38ee..4404a4b 100644
--- a/moo/configure.ac
+++ b/moo/configure.ac
@@ -172,6 +172,7 @@ AC_CHECK_FUNCS([gettimeofday settimeofday clock_gettime clock_settime getitimer
 AC_CHECK_FUNCS([backtrace backtrace_symbols])
 AC_CHECK_FUNCS([makecontext swapcontext getcontext setcontext])
 AC_CHECK_FUNCS([snprintf _vsnprintf _vsnwprintf])
+AC_CHECK_FUNCS([accept4])
 
 AC_CHECK_LIB([dyncall_s], [dcNewCallVM], 
 	[
diff --git a/moo/kernel/Socket.moo b/moo/kernel/Socket.moo
index c4210ee..74f12ce 100644
--- a/moo/kernel/Socket.moo
+++ b/moo/kernel/Socket.moo
@@ -457,6 +457,8 @@ error -> exception
 					(n asString & ' bytes read') dump.
 					data dump.
 				}.
+
+				sck writeBytes: #[ $h, $e, $l, $l, $o, $., $., $., C'\n' ].
 			}
 			while (true).
 		].
diff --git a/moo/lib/moo-cfg.h.in b/moo/lib/moo-cfg.h.in
index 1db8551..5f9916b 100644
--- a/moo/lib/moo-cfg.h.in
+++ b/moo/lib/moo-cfg.h.in
@@ -3,6 +3,9 @@
 /* Define if building universal (internal helper macro) */
 #undef AC_APPLE_UNIVERSAL_BUILD
 
+/* Define to 1 if you have the `accept4' function. */
+#undef HAVE_ACCEPT4
+
 /* Define to 1 if you have the `acosq' function. */
 #undef HAVE_ACOSQ
 
diff --git a/moo/mod/sck.c b/moo/mod/sck.c
index 6e132b0..b0aa2c5 100644
--- a/moo/mod/sck.c
+++ b/moo/mod/sck.c
@@ -150,7 +150,7 @@ static moo_pfrc_t pf_accept_socket (moo_t* moo, moo_ooi_t nargs)
 	oop_sck_t sck, newsck;
 	moo_oop_t arg;
 	sck_len_t addrlen;
-	int fd, newfd;
+	int fd, newfd, oldfl;
 
 	sck = (oop_sck_t)MOO_STACK_GETRCV(moo, nargs);
 	arg = MOO_STACK_GETARG(moo, nargs, 0);
@@ -169,7 +169,17 @@ static moo_pfrc_t pf_accept_socket (moo_t* moo, moo_ooi_t nargs)
 	}
 
 	addrlen = MOO_OBJ_GET_SIZE(arg);
+#if defined(SOCK_NONBLOCK) && defined(SOCK_CLOEXEC) && defined(HAVE_ACCEPT4)
+	newfd = accept4(fd, (struct sockaddr*)MOO_OBJ_GET_BYTE_SLOT(arg), &addrlen, SOCK_NONBLOCK | SOCK_CLOEXEC);
+#else
+	oldfl = fcntl(fd, F_GETFL, 0);
+	if (oldfl == -1 || fcntl(fd, F_SETFL, oldfl | O_NONBLOCK | O_CLOEXEC) == -1)
+	{
+		moo_seterrwithsyserr (moo, errno);
+		return MOO_PF_FAILURE;
+	}
 	newfd = accept(fd, (struct sockaddr*)MOO_OBJ_GET_BYTE_SLOT(arg), &addrlen);
+#endif
 	if (newfd == -1)
 	{
 		moo_seterrwithsyserr (moo, errno);