diff --git a/tests/compat-test b/tests/compat-test
index 5231173f..6ecf3114 100755
--- a/tests/compat-test
+++ b/tests/compat-test
@@ -248,6 +248,7 @@ $CRYPTSETUP luksOpen -d $KEYE $LOOPDEV $DEV_NAME || fail
 $CRYPTSETUP -q luksClose  $DEV_NAME || fail
 # open by volume key
 echo "key0" | $CRYPTSETUP -q luksFormat -s 256 --master-key-file $KEY1 $LOOPDEV || fail
+$CRYPTSETUP luksOpen --master-key-file /dev/urandom $LOOPDEV $DEV_NAME 2>/dev/null && fail
 $CRYPTSETUP luksOpen --master-key-file $KEY1 $LOOPDEV $DEV_NAME || fail
 $CRYPTSETUP -q luksClose  $DEV_NAME || fail