diff --git a/bin/tests/system/dnssec/tests.sh b/bin/tests/system/dnssec/tests.sh
index 3d2ccec420..9da14e3d02 100644
--- a/bin/tests/system/dnssec/tests.sh
+++ b/bin/tests/system/dnssec/tests.sh
@@ -2689,7 +2689,7 @@ awk '{
 	for (i=7;i<=NF;i++) printf("%s", $i);
 	printf("\n");
 }' < ns1/dsset-algroll$TP > canonical2.$n || ret=1
-diff -b canonical1.$n canonical2.$n > /dev/null 2>&1 || ret=1
+$DIFF -b canonical1.$n canonical2.$n > /dev/null 2>&1 || ret=1
 n=$((n+1))
 test "$ret" -eq 0 || echo_i "failed"
 status=$((status+ret))
diff --git a/bin/tests/system/keepalive/tests.sh b/bin/tests/system/keepalive/tests.sh
index 7983aa1a94..7ff95a889e 100644
--- a/bin/tests/system/keepalive/tests.sh
+++ b/bin/tests/system/keepalive/tests.sh
@@ -70,7 +70,7 @@ echo_i "checking re-configured value ($n)"
 ret=0
 n=`expr $n + 1`
 $RNDCCMD tcp-timeouts 300 300 300 200 > output
-diff -b output expected || ret=1
+$DIFF -b output expected || ret=1
 $DIG $DIGOPTS +vc +keepalive foo.example @10.53.0.2 > dig.out.test$n
 grep "; TCP KEEPALIVE: 20.0 secs" dig.out.test$n > /dev/null || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
diff --git a/bin/tests/system/names/tests.sh b/bin/tests/system/names/tests.sh
index 23202268cc..8b88ed8243 100644
--- a/bin/tests/system/names/tests.sh
+++ b/bin/tests/system/names/tests.sh
@@ -29,7 +29,7 @@ cat dig.compdis.test  |grep -v ';;' |sort > dig.compdis.sorted.test
 # the compression disabled message should be at least twice as large as with
 # compression disabled, but the content should be the same
 echo_i "Checking if responses are identical other than in message size"
-diff dig.compdis.sorted.test dig.compen.sorted.test >/dev/null
+$DIFF dig.compdis.sorted.test dig.compen.sorted.test >/dev/null
 ret=$?
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
diff --git a/bin/tests/system/pipelined/tests.sh b/bin/tests/system/pipelined/tests.sh
index a6720ce656..61f1ff70cd 100644
--- a/bin/tests/system/pipelined/tests.sh
+++ b/bin/tests/system/pipelined/tests.sh
@@ -22,8 +22,8 @@ ret=0
 $PIPEQUERIES -p ${PORT} < input > raw || ret=1
 awk '{ print $1 " " $5 }' < raw > output
 sort < output > output-sorted
-diff ref output-sorted || { ret=1 ; echo_i "diff sorted failed"; }
-diff ref output > /dev/null && { ret=1 ; echo_i "diff out of order failed"; }
+$DIFF ref output-sorted || { ret=1 ; echo_i "diff sorted failed"; }
+$DIFF ref output > /dev/null && { ret=1 ; echo_i "diff out of order failed"; }
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
 
@@ -36,8 +36,8 @@ ret=0
 $MDIG $MDIGOPTS +noall +answer +vc -f input -b 10.53.0.4 @10.53.0.4 > raw.mdig
 awk '{ print $1 " " $5 }' < raw.mdig > output.mdig
 sort < output.mdig > output-sorted.mdig
-diff ref output-sorted.mdig || { ret=1 ; echo_i "diff sorted failed"; }
-diff ref output.mdig > /dev/null && { ret=1 ; echo_i "diff out of order failed"; }
+$DIFF ref output-sorted.mdig || { ret=1 ; echo_i "diff sorted failed"; }
+$DIFF ref output.mdig > /dev/null && { ret=1 ; echo_i "diff out of order failed"; }
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
 
@@ -45,7 +45,7 @@ echo_i "check keep-response-order"
 ret=0
 $PIPEQUERIES -p ${PORT} ++ < inputb > rawb || ret=1
 awk '{ print $1 " " $5 }' < rawb > outputb
-diff refb outputb || ret=1
+$DIFF refb outputb || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
 
@@ -53,7 +53,7 @@ echo_i "check keep-response-order using mdig"
 ret=0
 $MDIG $MDIGOPTS +noall +answer +vc -f inputb -b 10.53.0.7 @10.53.0.4 > rawb.mdig
 awk '{ print $1 " " $5 }' < rawb.mdig > outputb.mdig
-diff refb outputb.mdig || ret=1
+$DIFF refb outputb.mdig || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
 
diff --git a/bin/tests/system/qmin/tests.sh b/bin/tests/system/qmin/tests.sh
index baa6798356..b67f3511e0 100755
--- a/bin/tests/system/qmin/tests.sh
+++ b/bin/tests/system/qmin/tests.sh
@@ -27,15 +27,15 @@ $DIG $DIGOPTS icky.icky.icky.ptang.zoop.boing.good. @10.53.0.5 > dig.out.test$n
 grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "icky.icky.icky.ptang.zoop.boing.good. 1	IN A	192.0.2.1" dig.out.test$n > /dev/null || ret=1
 sleep 1
-cat << __EOF | diff ans2/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log - > /dev/null || ret=1
 ADDR icky.icky.icky.ptang.zoop.boing.good.
 ADDR ns3.good.
 ADDR ns3.good.
 ADDR a.bit.longer.ns.name.good.
 ADDR a.bit.longer.ns.name.good.
 __EOF
-echo "ADDR icky.icky.icky.ptang.zoop.boing.good." | diff ans3/query.log - > /dev/null || ret=1
-echo "ADDR icky.icky.icky.ptang.zoop.boing.good." | diff ans4/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.good." | $DIFF ans3/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.good." | $DIFF ans4/query.log - > /dev/null || ret=1
 for ans in ans2 ans3 ans4; do mv -f $ans/query.log query-$ans-$n.log 2>/dev/null || true; done
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
@@ -49,15 +49,15 @@ $DIG $DIGOPTS icky.icky.icky.ptang.zoop.boing.bad. @10.53.0.5 > dig.out.test$n
 grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "icky.icky.icky.ptang.zoop.boing.bad. 1 IN A	192.0.2.1" dig.out.test$n > /dev/null || ret=1
 sleep 1
-cat << __EOF | diff ans2/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log - > /dev/null || ret=1
 ADDR icky.icky.icky.ptang.zoop.boing.bad.
 ADDR ns3.bad.
 ADDR ns3.bad.
 ADDR a.bit.longer.ns.name.bad.
 ADDR a.bit.longer.ns.name.bad.
 __EOF
-echo "ADDR icky.icky.icky.ptang.zoop.boing.bad." | diff ans3/query.log - > /dev/null || ret=1
-echo "ADDR icky.icky.icky.ptang.zoop.boing.bad." | diff ans4/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.bad." | $DIFF ans3/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.bad." | $DIFF ans4/query.log - > /dev/null || ret=1
 for ans in ans2 ans3 ans4; do mv -f $ans/query.log query-$ans-$n.log 2>/dev/null || true; done
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
@@ -72,15 +72,15 @@ sleep 5
 grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "icky.icky.icky.ptang.zoop.boing.slow. 1	IN A	192.0.2.1" dig.out.test$n > /dev/null || ret=1
 sleep 1
-cat << __EOF | diff ans2/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log - > /dev/null || ret=1
 ADDR icky.icky.icky.ptang.zoop.boing.slow.
 ADDR ns3.slow.
 ADDR ns3.slow.
 ADDR a.bit.longer.ns.name.slow.
 ADDR a.bit.longer.ns.name.slow.
 __EOF
-echo "ADDR icky.icky.icky.ptang.zoop.boing.slow." | diff ans3/query.log - > /dev/null || ret=1
-echo "ADDR icky.icky.icky.ptang.zoop.boing.slow." | diff ans4/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.slow." | $DIFF ans3/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.slow." | $DIFF ans4/query.log - > /dev/null || ret=1
 for ans in ans2 ans3 ans4; do mv -f $ans/query.log query-$ans-$n.log 2>/dev/null || true; done
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
@@ -95,15 +95,15 @@ sleep 5
 grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "icky.icky.icky.ptang.zoop.boing.ugly. 1	IN A	192.0.2.1" dig.out.test$n > /dev/null || ret=1
 sleep 1
-cat << __EOF | diff ans2/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log - > /dev/null || ret=1
 ADDR icky.icky.icky.ptang.zoop.boing.ugly.
 ADDR ns3.ugly.
 ADDR ns3.ugly.
 ADDR a.bit.longer.ns.name.ugly.
 ADDR a.bit.longer.ns.name.ugly.
 __EOF
-echo "ADDR icky.icky.icky.ptang.zoop.boing.ugly." | diff ans3/query.log - > /dev/null || ret=1
-echo "ADDR icky.icky.icky.ptang.zoop.boing.ugly." | diff ans4/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.ugly." | $DIFF ans3/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.ugly." | $DIFF ans4/query.log - > /dev/null || ret=1
 for ans in ans2 ans3 ans4; do mv -f $ans/query.log query-$ans-$n.log 2>/dev/null || true; done
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
@@ -118,7 +118,7 @@ grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "icky.icky.icky.ptang.zoop.boing.good. 1	IN A	192.0.2.1" dig.out.test$n > /dev/null || ret=1
 sleep 1
 sort ans2/query.log > ans2/query.log.sorted
-cat << __EOF | diff ans2/query.log.sorted - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log.sorted - > /dev/null || ret=1
 ADDR a.bit.longer.ns.name.good.
 ADDR a.bit.longer.ns.name.good.
 ADDR ns2.good.
@@ -128,12 +128,12 @@ NS boing.good.
 NS good.
 NS zoop.boing.good.
 __EOF
-cat << __EOF | diff ans3/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans3/query.log - > /dev/null || ret=1
 NS zoop.boing.good.
 NS ptang.zoop.boing.good.
 NS icky.ptang.zoop.boing.good.
 __EOF
-cat << __EOF | diff ans4/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans4/query.log - > /dev/null || ret=1
 NS icky.ptang.zoop.boing.good.
 NS icky.icky.ptang.zoop.boing.good.
 ADDR icky.icky.icky.ptang.zoop.boing.good.
@@ -151,7 +151,7 @@ $DIG $DIGOPTS icky.icky.icky.ptang.zoop.boing.bad. @10.53.0.6 > dig.out.test$n
 grep "status: NXDOMAIN" dig.out.test$n > /dev/null || ret=1
 sleep 1
 sort ans2/query.log > ans2/query.log.sorted
-cat << __EOF | diff ans2/query.log.sorted - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log.sorted - > /dev/null || ret=1
 ADDR ns2.bad.
 NS bad.
 NS boing.bad.
@@ -170,7 +170,7 @@ grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "icky.icky.icky.ptang.zoop.boing.bad. 1 IN A	192.0.2.1" dig.out.test$n > /dev/null || ret=1
 sleep 1
 sort ans2/query.log > ans2/query.log.sorted
-cat << __EOF | diff ans2/query.log.sorted - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log.sorted - > /dev/null || ret=1
 ADDR a.bit.longer.ns.name.bad.
 ADDR a.bit.longer.ns.name.bad.
 ADDR icky.icky.icky.ptang.zoop.boing.bad.
@@ -180,8 +180,8 @@ ADDR ns3.bad.
 NS bad.
 NS boing.bad.
 __EOF
-echo "ADDR icky.icky.icky.ptang.zoop.boing.bad." | diff ans3/query.log - > /dev/null || ret=1
-echo "ADDR icky.icky.icky.ptang.zoop.boing.bad." | diff ans4/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.bad." | $DIFF ans3/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.bad." | $DIFF ans4/query.log - > /dev/null || ret=1
 for ans in ans2 ans3 ans4; do mv -f $ans/query.log query-$ans-$n.log 2>/dev/null || true; done
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
@@ -195,7 +195,7 @@ $DIG $DIGOPTS icky.icky.icky.ptang.zoop.boing.ugly. @10.53.0.6 > dig.out.test$n
 grep "status: SERVFAIL" dig.out.test$n > /dev/null || ret=1
 sleep 1
 sort ans2/query.log > ans2/query.log.sorted
-cat << __EOF | diff ans2/query.log.sorted - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log.sorted - > /dev/null || ret=1
 ADDR ns2.ugly.
 NS boing.ugly.
 NS boing.ugly.
@@ -216,7 +216,7 @@ grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "icky.icky.icky.ptang.zoop.boing.ugly. 1	IN A	192.0.2.1" dig.out.test$n > /dev/null || ret=1
 sleep 1
 sort ans2/query.log > ans2/query.log.sorted
-cat << __EOF | diff ans2/query.log.sorted - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log.sorted - > /dev/null || ret=1
 ADDR a.bit.longer.ns.name.ugly.
 ADDR a.bit.longer.ns.name.ugly.
 ADDR icky.icky.icky.ptang.zoop.boing.ugly.
@@ -227,8 +227,8 @@ NS boing.ugly.
 NS boing.ugly.
 NS ugly.
 __EOF
-echo "ADDR icky.icky.icky.ptang.zoop.boing.ugly." | diff ans3/query.log - > /dev/null || ret=1
-echo "ADDR icky.icky.icky.ptang.zoop.boing.ugly." | diff ans4/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.ugly." | $DIFF ans3/query.log - > /dev/null || ret=1
+echo "ADDR icky.icky.icky.ptang.zoop.boing.ugly." | $DIFF ans4/query.log - > /dev/null || ret=1
 for ans in ans2 ans3 ans4; do mv -f $ans/query.log query-$ans-$n.log 2>/dev/null || true; done
 if [ $ret != 0 ]; then echo_i "failed"; fi
 status=`expr $status + $ret`
@@ -251,7 +251,7 @@ sleep 5
 grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "icky.icky.icky.ptang.zoop.boing.slow. 1	IN A	192.0.2.1" dig.out.test$n > /dev/null || ret=1
 sort ans2/query.log > ans2/query.log.sorted
-cat << __EOF | diff ans2/query.log.sorted - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log.sorted - > /dev/null || ret=1
 ADDR a.bit.longer.ns.name.slow.
 ADDR a.bit.longer.ns.name.slow.
 ADDR ns2.slow.
@@ -261,12 +261,12 @@ NS boing.slow.
 NS slow.
 NS zoop.boing.slow.
 __EOF
-cat << __EOF | diff ans3/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans3/query.log - > /dev/null || ret=1
 NS zoop.boing.slow.
 NS ptang.zoop.boing.slow.
 NS icky.ptang.zoop.boing.slow.
 __EOF
-cat << __EOF | diff ans4/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans4/query.log - > /dev/null || ret=1
 NS icky.ptang.zoop.boing.slow.
 NS icky.icky.ptang.zoop.boing.slow.
 ADDR icky.icky.icky.ptang.zoop.boing.slow.
@@ -285,7 +285,7 @@ grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.f.4.0.1.0.0.2.ip6.arpa. 1 IN PTR nee.com." dig.out.test$n > /dev/null || ret=1
 sleep 1
 grep -v ADDR ans2/query.log > ans2/query.log.trimmed
-cat << __EOF | diff ans2/query.log.trimmed - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log.trimmed - > /dev/null || ret=1
 NS 1.0.0.2.ip6.arpa.
 NS 8.f.4.0.1.0.0.2.ip6.arpa.
 NS 0.0.0.0.8.f.4.0.1.0.0.2.ip6.arpa.
@@ -307,7 +307,7 @@ grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "more.icky.icky.icky.ptang.zoop.boing.good. 1 IN	A 192.0.2.2" dig.out.test$n > /dev/null || ret=1
 sleep 1
 sort ans2/query.log > ans2/query.log.sorted
-cat << __EOF | diff ans2/query.log.sorted - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log.sorted - > /dev/null || ret=1
 ADDR a.bit.longer.ns.name.good.
 ADDR a.bit.longer.ns.name.good.
 ADDR ns2.good.
@@ -317,13 +317,13 @@ NS boing.good.
 NS good.
 NS zoop.boing.good.
 __EOF
-cat << __EOF | diff ans3/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans3/query.log - > /dev/null || ret=1
 NS zoop.boing.good.
 NS ptang.zoop.boing.good.
 NS icky.ptang.zoop.boing.good.
 __EOF
 # There's no NS icky.icky.icky.ptang.zoop.boing.good. query - we skipped it.
-cat << __EOF | diff ans4/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans4/query.log - > /dev/null || ret=1
 NS icky.ptang.zoop.boing.good.
 NS icky.icky.ptang.zoop.boing.good.
 ADDR more.icky.icky.icky.ptang.zoop.boing.good.
@@ -341,7 +341,7 @@ $DIG $DIGOPTS a.bit.longer.ns.name.fwd. @10.53.0.7 > dig.out.test$n
 grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
 grep "a.bit.longer.ns.name.fwd. 1	IN	A	10.53.0.4" dig.out.test$n >/dev/null || ret=1
 sleep 1
-cat << __EOF | diff ans2/query.log - > /dev/null || ret=1
+cat << __EOF | $DIFF ans2/query.log - > /dev/null || ret=1
 ADDR a.bit.longer.ns.name.fwd.
 __EOF
 for ans in ans2; do mv -f $ans/query.log query-$ans-$n.log 2>/dev/null || true; done