diff --git a/bumblebee-status b/bumblebee-status
index 698bcf8..4a9f7fb 100755
--- a/bumblebee-status
+++ b/bumblebee-status
@@ -75,6 +75,8 @@ def handle_events(config, update_lock):
 
 
 def main():
+    global started
+
     config = core.config.Config(sys.argv[1:])
     level = logging.DEBUG if config.debug() else logging.ERROR
     if config.logfile():
@@ -97,6 +99,8 @@ def main():
     core.input.register(None, core.input.WHEEL_UP, "i3-msg workspace prev_on_output")
     core.input.register(None, core.input.WHEEL_DOWN, "i3-msg workspace next_on_output")
 
+    core.event.trigger("start")
+
     update_lock = threading.Lock()
     event_thread = threading.Thread(target=handle_events, args=(config, update_lock, ))
     event_thread.daemon = True
@@ -127,7 +131,6 @@ def main():
     if util.format.asbool(config.get("engine.collapsible", True)) == True:
         core.input.register(None, core.input.MIDDLE_MOUSE, output.toggle_minimize)
 
-    core.event.trigger("start")
     started = True
     signal.signal(10, sig_USR1_handler)
     while True:
diff --git a/bumblebee_status/core/output.py b/bumblebee_status/core/output.py
index cee579f..1bd5038 100644
--- a/bumblebee_status/core/output.py
+++ b/bumblebee_status/core/output.py
@@ -1,6 +1,7 @@
 import sys
 import json
 import time
+import threading
 
 import core.theme
 import core.event
@@ -145,6 +146,7 @@ class i3(object):
         self.__content = {}
         self.__theme = theme
         self.__config = config
+        self.__lock = threading.Lock()
         core.event.register("update", self.update)
         core.event.register("start", self.draw, "start")
         core.event.register("draw", self.draw, "statusline")
@@ -176,14 +178,15 @@ class i3(object):
             self.__content[widget_id]["minimized"] = not self.__content[widget_id]["minimized"]
 
     def draw(self, what, args=None):
-        cb = getattr(self, what)
-        data = cb(args) if args else cb()
-        if "blocks" in data:
-            sys.stdout.write(json.dumps(data["blocks"], default=dump_json))
-        if "suffix" in data:
-            sys.stdout.write(data["suffix"])
-        sys.stdout.write("\n")
-        sys.stdout.flush()
+        with self.__lock:
+            cb = getattr(self, what)
+            data = cb(args) if args else cb()
+            if "blocks" in data:
+                sys.stdout.write(json.dumps(data["blocks"], default=dump_json))
+            if "suffix" in data:
+                sys.stdout.write(data["suffix"])
+            sys.stdout.write("\n")
+            sys.stdout.flush()
 
     def start(self):
         return {
@@ -244,6 +247,10 @@ class i3(object):
         return blocks
 
     def update(self, affected_modules=None, redraw_only=False, force=False):
+        with self.__lock:
+            self.update2(affected_modules, redraw_only, force)
+
+    def update2(self, affected_modules=None, redraw_only=False, force=False):
         now = time.time()
         for module in self.__modules:
             if affected_modules and not module.id in affected_modules: