diff --git a/gunicorn/util.py b/gunicorn/util.py
index 751deea71..40ea00728 100644
--- a/gunicorn/util.py
+++ b/gunicorn/util.py
@@ -256,9 +256,10 @@ def parse_address(netloc, default_port='8000'):
 
 
 def close_on_exec(fd):
-    flags = fcntl.fcntl(fd, fcntl.F_GETFD)
-    flags |= fcntl.FD_CLOEXEC
-    fcntl.fcntl(fd, fcntl.F_SETFD, flags)
+    # available since Python 3.4, equivalent to either:
+    # ioctl(fd, FIOCLEX)
+    # fcntl(fd, fcntl.F_SETFD, fcntl.FD_CLOEXEC)
+    os.set_inheritable(fd, False)
 
 
 def set_non_blocking(fd):