Index: tests/ppid-p.tst
--- tests/ppid-p.tst.orig
+++ tests/ppid-p.tst
@@ -4,7 +4,7 @@ posix="true"
 
 test_OE -e 0 'PPID is parent process ID'
 echo $PPID >variable.out
-echo $(ps -o ppid= $$) >ps.out
+echo $(ps -o ppid= -p $$) >ps.out
 diff variable.out ps.out
 __IN__
 
