diff --git a/platform/kindle/koreader.sh b/platform/kindle/koreader.sh
index 0d9362b4c..a9dd54b35 100755
--- a/platform/kindle/koreader.sh
+++ b/platform/kindle/koreader.sh
@@ -208,7 +208,7 @@ fi
 ./reader.lua "$@" 2> crash.log
 
 # clean up our own process tree in case the reader crashed (if needed, to avoid flooding KUAL's log)
-if pkill -0 reader.lua ; then
+if pidof reader.lua > /dev/null 2>&1 ; then
 	logmsg "Sending a SIGTERM to stray KOreader processes . . ."
 	killall -TERM reader.lua
 fi
diff --git a/platform/kobo/koreader.sh b/platform/kobo/koreader.sh
index 91539f97a..3983477e7 100755
--- a/platform/kobo/koreader.sh
+++ b/platform/kobo/koreader.sh
@@ -89,7 +89,7 @@ else
 	# if we were called from advboot then we must reboot to go to the menu
 	# NOTE: This is actually achieved by checking if KSM is running:
 	#       This might lead to false-positives if you use neither KSM nor advboot to launch KOReader *without nickel running*.
-	if ! pidof ksmhome.sh > /dev/null 2>&1 ; then
+	if ! pgrep -f ksmhome.sh > /dev/null 2>&1 ; then
 		reboot
 	fi
 fi