diff --git a/gunicorn/arbiter.py b/gunicorn/arbiter.py
index 7eaa2c17..f7f86f00 100644
--- a/gunicorn/arbiter.py
+++ b/gunicorn/arbiter.py
@@ -494,7 +494,7 @@ class Arbiter(object):
         workers = list(self.WORKERS.items())
         for (pid, worker) in workers:
             try:
-                if time.time() - worker.tmp.last_update() <= self.timeout:
+                if time.monotonic() - worker.tmp.last_update() <= self.timeout:
                     continue
             except (OSError, ValueError):
                 continue
diff --git a/gunicorn/workers/workertmp.py b/gunicorn/workers/workertmp.py
index 22aaef34..66defe94 100644
--- a/gunicorn/workers/workertmp.py
+++ b/gunicorn/workers/workertmp.py
@@ -4,6 +4,7 @@
 # See the NOTICE for more information.
 
 import os
+import time
 import platform
 import tempfile
 
@@ -35,14 +36,12 @@ class WorkerTmp(object):
             os.close(fd)
             raise
 
-        self.spinner = 0
-
     def notify(self):
-        self.spinner = (self.spinner + 1) % 2
-        os.fchmod(self._tmp.fileno(), self.spinner)
+        new_time = time.monotonic()
+        os.utime(self._tmp.name, (new_time, new_time))
 
     def last_update(self):
-        return os.fstat(self._tmp.fileno()).st_ctime
+        return os.fstat(self._tmp.fileno()).st_mtime
 
     def fileno(self):
         return self._tmp.fileno()