diff --git a/socketIO_client/__init__.py b/socketIO_client/__init__.py
index 8979801..c27009b 100644
--- a/socketIO_client/__init__.py
+++ b/socketIO_client/__init__.py
@@ -250,7 +250,7 @@ class SocketIO(object):
                     self._process_events()
                 except TimeoutError:
                     pass
-                self.heartbeat_pacemaker.send(elapsed_time)
+                self.heartbeat_pacemaker.next()
             except ConnectionError as e:
                 try:
                     warning = Exception('[connection error] %s' % e)
@@ -344,11 +344,11 @@ class SocketIO(object):
         return transport
 
     def _make_heartbeat_pacemaker(self, heartbeat_interval):
-        heartbeat_time = 0
+        heartbeat_time = time.time()
         while True:
-            elapsed_time = (yield)
-            if elapsed_time - heartbeat_time > heartbeat_interval:
-                heartbeat_time = elapsed_time
+            yield
+            if time.time() - heartbeat_time > heartbeat_interval:
+                heartbeat_time = time.time()
                 self._transport.send_heartbeat()
 
     def get_namespace(self, path=''):