diff --git a/AnyEvent-I3/lib/AnyEvent/I3.pm b/AnyEvent-I3/lib/AnyEvent/I3.pm
index 198c41c9..ae9e5bea 100644
--- a/AnyEvent-I3/lib/AnyEvent/I3.pm
+++ b/AnyEvent-I3/lib/AnyEvent/I3.pm
@@ -100,11 +100,12 @@ use constant TYPE_GET_VERSION => 7;
 use constant TYPE_GET_BINDING_MODES => 8;
 use constant TYPE_GET_CONFIG => 9;
 use constant TYPE_SEND_TICK => 10;
+use constant TYPE_SYNC => 11;
 
 our %EXPORT_TAGS = ( 'all' => [
     qw(i3 TYPE_RUN_COMMAND TYPE_COMMAND TYPE_GET_WORKSPACES TYPE_SUBSCRIBE TYPE_GET_OUTPUTS
        TYPE_GET_TREE TYPE_GET_MARKS TYPE_GET_BAR_CONFIG TYPE_GET_VERSION
-       TYPE_GET_BINDING_MODES TYPE_GET_CONFIG TYPE_SEND_TICK)
+       TYPE_GET_BINDING_MODES TYPE_GET_CONFIG TYPE_SEND_TICK TYPE_SYNC)
 ] );
 
 our @EXPORT_OK = ( @{ $EXPORT_TAGS{all} } );
@@ -534,6 +535,19 @@ sub send_tick {
     $self->message(TYPE_SEND_TICK, $payload);
 }
 
+=head2 sync
+
+Sends an i3 sync event. Requires i3 >= 4.16
+
+=cut
+sub sync {
+    my ($self, $payload) = @_;
+
+    $self->_ensure_connection;
+
+    $self->message(TYPE_SYNC, $payload);
+}
+
 =head2 command($content)
 
 Makes i3 execute the given command
diff --git a/docs/ipc b/docs/ipc
index 8b767ade..f011e773 100644
--- a/docs/ipc
+++ b/docs/ipc
@@ -65,6 +65,7 @@ to do that).
 | 8 | +GET_BINDING_MODES+ | <<_binding_modes_reply,BINDING_MODES>> | Gets the names of all currently configured binding modes.
 | 9 | +GET_CONFIG+ | <<_config_reply,CONFIG>> | Returns the last loaded i3 config.
 | 10 | +SEND_TICK+ | <<_tick_reply,TICK>> | Sends a tick event with the specified payload.
+| 11 | +SYNC+ | <<_sync_reply,SYNC>> | Sends an i3 sync event with the specified random value to the specified window.
 |======================================================
 
 So, a typical message could look like this:
@@ -654,6 +655,18 @@ events generated prior to the +SEND_TICK+ message (happened-before relation).
 { "success": true }
 -------------------
 
+[[_sync_reply]]
+=== SYNC reply
+
+The reply is a map containing the "success" member. After the reply was
+received, the https://i3wm.org/docs/testsuite.html#i3_sync[i3 sync message] was
+responded to.
+
+*Example:*
+-------------------
+{ "success": true }
+-------------------
+
 == Events
 
 [[events]]
diff --git a/include/i3/ipc.h b/include/i3/ipc.h
index 9e0280c9..0c57f7fd 100644
--- a/include/i3/ipc.h
+++ b/include/i3/ipc.h
@@ -63,6 +63,9 @@ typedef struct i3_ipc_header {
 /** Send a tick event to all subscribers. */
 #define I3_IPC_MESSAGE_TYPE_SEND_TICK 10
 
+/** Trigger an i3 sync protocol message via IPC. */
+#define I3_IPC_MESSAGE_TYPE_SYNC 11
+
 /*
  * Messages from i3 to clients
  *
@@ -78,6 +81,7 @@ typedef struct i3_ipc_header {
 #define I3_IPC_REPLY_TYPE_BINDING_MODES 8
 #define I3_IPC_REPLY_TYPE_CONFIG 9
 #define I3_IPC_REPLY_TYPE_TICK 10
+#define I3_IPC_REPLY_TYPE_SYNC 11
 
 /*
  * Events from i3 to clients. Events have the first bit set high.
diff --git a/src/ipc.c b/src/ipc.c
index 6b6383ec..d422217e 100644
--- a/src/ipc.c
+++ b/src/ipc.c
@@ -1173,9 +1173,68 @@ IPC_HANDLER(send_tick) {
     DLOG("Sent tick event\n");
 }
 
+struct sync_state {
+    char *last_key;
+    uint32_t rnd;
+    xcb_window_t window;
+};
+
+static int _sync_json_key(void *extra, const unsigned char *val, size_t len) {
+    struct sync_state *state = extra;
+    FREE(state->last_key);
+    state->last_key = scalloc(len + 1, 1);
+    memcpy(state->last_key, val, len);
+    return 1;
+}
+
+static int _sync_json_int(void *extra, long long val) {
+    struct sync_state *state = extra;
+    if (strcasecmp(state->last_key, "rnd") == 0) {
+        state->rnd = val;
+    } else if (strcasecmp(state->last_key, "window") == 0) {
+        state->window = (xcb_window_t)val;
+    }
+    return 1;
+}
+
+IPC_HANDLER(sync) {
+    yajl_handle p;
+    yajl_status stat;
+
+    /* Setup the JSON parser */
+    static yajl_callbacks callbacks = {
+        .yajl_map_key = _sync_json_key,
+        .yajl_integer = _sync_json_int,
+    };
+
+    struct sync_state state;
+    memset(&state, '\0', sizeof(struct sync_state));
+    p = yalloc(&callbacks, (void *)&state);
+    stat = yajl_parse(p, (const unsigned char *)message, message_size);
+    FREE(state.last_key);
+    if (stat != yajl_status_ok) {
+        unsigned char *err;
+        err = yajl_get_error(p, true, (const unsigned char *)message,
+                             message_size);
+        ELOG("YAJL parse error: %s\n", err);
+        yajl_free_error(p, err);
+
+        const char *reply = "{\"success\":false}";
+        ipc_send_message(fd, strlen(reply), I3_IPC_REPLY_TYPE_SYNC, (const uint8_t *)reply);
+        yajl_free(p);
+        return;
+    }
+    yajl_free(p);
+
+    DLOG("received IPC sync request (rnd = %d, window = 0x%08x)\n", state.rnd, state.window);
+    sync_respond(state.window, state.rnd);
+    const char *reply = "{\"success\":true}";
+    ipc_send_message(fd, strlen(reply), I3_IPC_REPLY_TYPE_SYNC, (const uint8_t *)reply);
+}
+
 /* The index of each callback function corresponds to the numeric
  * value of the message type (see include/i3/ipc.h) */
-handler_t handlers[11] = {
+handler_t handlers[12] = {
     handle_run_command,
     handle_get_workspaces,
     handle_subscribe,
@@ -1187,6 +1246,7 @@ handler_t handlers[11] = {
     handle_get_binding_modes,
     handle_get_config,
     handle_send_tick,
+    handle_sync,
 };
 
 /*