diff --git a/unittest/Makefile b/unittest/Makefile
index 11fe161e..0adf7156 100644
--- a/unittest/Makefile
+++ b/unittest/Makefile
@@ -10,6 +10,7 @@ unittest: ../src/parallel tests-to-run/* wanted-results/*
 	expect -c 'spawn cat; puts "expect is installed"' || (echo expect is required for unittest; /bin/false)
 	echo | pv -qL 10 || (echo pv is required for unittest; /bin/false)
 	echo | script -c echo -q /dev/null || (echo script is required for unittest; /bin/false)
+	niceload true || (echo niceload is required for unittest; /bin/false)
 	time sh Start.sh
 	date
 
diff --git a/unittest/tests-to-run/test12.sh b/unittest/tests-to-run/test12.sh
index bd9d6147..c948babe 100755
--- a/unittest/tests-to-run/test12.sh
+++ b/unittest/tests-to-run/test12.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-PAR=parallel
-
 # Test if we can deal with output > 4 GB
-echo | $PAR 'dd if=/dev/zero count=43 bs=100000k; echo 1; echo 2' | md5sum
+echo | niceload -l=1.5 parallel -q perl -e '$a="x"x1000000;for(0..4300){print $a}' | md5sum
+# dd does not work with niceload (no idea why)
+#echo | parallel 'dd if=/dev/zero count=43 bs=100000k; echo 1; echo 2' | md5sum
diff --git a/unittest/wanted-results/test12 b/unittest/wanted-results/test12
index 31eae36e..45d9f4d7 100644
--- a/unittest/wanted-results/test12
+++ b/unittest/wanted-results/test12
@@ -1 +1 @@
-75da7edc12b129d109af92592c61da56  -
+46a318993dfc8e2afd71ff2bc6f605f1  -