diff --git a/iotop/data.py b/iotop/data.py
index f5496d0..665397c 100644
--- a/iotop/data.py
+++ b/iotop/data.py
@@ -43,7 +43,6 @@ except (ImportError, RuntimeError):
 # Check for requirements:
 #   o Linux >= 2.6.20 with I/O accounting and VM event counters
 #
-
 ioaccounting = os.path.exists('/proc/self/io')
 
 try:
@@ -90,7 +89,7 @@ class Stats(DumpableObject):
         ('cancelled_write_bytes', 264)
     ]
 
-    has_blkio_delay_total = False
+    has_blkio_delay_total = None
 
     def __init__(self, task_stats_buffer):
         sd = self.__dict__
@@ -101,7 +100,7 @@ class Stats(DumpableObject):
         # This is a heuristic to detect if CONFIG_TASK_DELAY_ACCT is enabled in
         # the kernel.
         if not Stats.has_blkio_delay_total:
-            Stats.has_blkio_delay_total = self.blkio_delay_total != 0
+            Stats.has_blkio_delay_total = sysctl_task_delayacct()
 
     def accumulate(self, other_stats, destination, coeff=1):
         """Update destination from operator(self, other_stats)"""
diff --git a/iotop/ui.py b/iotop/ui.py
index 77f82c7..d9dc044 100644
--- a/iotop/ui.py
+++ b/iotop/ui.py
@@ -514,7 +514,7 @@ class IOTopUI(object):
         else:
             self.win.erase()
 
-            if self.has_swapin_io:
+            if self.has_swapin_io is not False:
                 status_msg = None
             else:
                 status_msg = ('CONFIG_TASK_DELAY_ACCT '