diff --git a/artiq/devices/runtime.py b/artiq/devices/runtime.py
index ca197fd6c..9aee65d54 100644
--- a/artiq/devices/runtime.py
+++ b/artiq/devices/runtime.py
@@ -6,7 +6,8 @@ lt.initialize_all()
 _syscalls = [
 	("rpc",			"i+:i"),
 	("gpio_set",	"ii:v"),
-	("rtio_set",	"iii:v")
+	("rtio_set",	"iii:v"),
+	("rtio_sync",	"i:v"),
 ]
 
 def _str_to_functype(s):
diff --git a/soc/runtime/main.c b/soc/runtime/main.c
index d7e2b1e98..fe046fe88 100644
--- a/soc/runtime/main.c
+++ b/soc/runtime/main.c
@@ -139,10 +139,17 @@ static void rtio_set(int timestamp, int channel, int value)
 	rtio_o_we_write(1);
 }
 
+static void rtio_sync(int channel)
+{
+	rtio_chan_sel_write(channel);
+	while(rtio_o_level_read() != 0);
+}
+
 static const struct symbol syscalls[] = {
 	{"__syscall_rpc",			rpc},
 	{"__syscall_gpio_set",		gpio_set},
 	{"__syscall_rtio_set",		rtio_set},
+	{"__syscall_rtio_sync",		rtio_sync},
 	{NULL, NULL}
 };