diff --git a/bin/dig/nslookup.c b/bin/dig/nslookup.c
index 95c0767365..d5ce6f7900 100644
--- a/bin/dig/nslookup.c
+++ b/bin/dig/nslookup.c
@@ -621,8 +621,6 @@ static void
 setoption(char *opt) {
 	size_t l = strlen(opt);
 
-	debugging = true;
-
 #define CHECKOPT(A, N) \
 	((l >= N) && (l < sizeof(A)) && (strncasecmp(opt, A, l) == 0))
 
diff --git a/bin/tests/system/nslookup/clean.sh b/bin/tests/system/nslookup/clean.sh
index 5aad8dda5a..5c2b4a9bb8 100644
--- a/bin/tests/system/nslookup/clean.sh
+++ b/bin/tests/system/nslookup/clean.sh
@@ -11,6 +11,7 @@
 
 rm -f ns1/example.db
 rm -f nslookup.out*
+rm -f nslookup.err*
 rm -f ns*/named.lock
 rm -f ns*/named.memstats
 rm -f ns*/named.run
diff --git a/bin/tests/system/nslookup/tests.sh b/bin/tests/system/nslookup/tests.sh
index 856dcc7d43..e3dd0f5264 100644
--- a/bin/tests/system/nslookup/tests.sh
+++ b/bin/tests/system/nslookup/tests.sh
@@ -11,101 +11,116 @@
 # See the COPYRIGHT file distributed with this work for additional
 # information regarding copyright ownership.
 
+# shellcheck disable=SC2086
 . ../conf.sh
 
 status=0
 n=0
 
-n=`expr $n + 1`
+n=$((n+1))
 echo_i "Check that domain names that are too big when applying a search list entry are handled cleanly ($n)"
 ret=0
 l=012345678901234567890123456789012345678901234567890123456789012
 t=0123456789012345678901234567890123456789012345678901234567890
 d=$l.$l.$l.$t
-$NSLOOKUP -port=${PORT} -domain=$d -type=soa example 10.53.0.1 > nslookup.out${n} || ret=1
+$NSLOOKUP -port=${PORT} -domain=$d -type=soa example 10.53.0.1 2> nslookup.err${n} > nslookup.out${n} || ret=1
+lines=$(wc -l < nslookup.err${n})
+test $lines -eq 0 || ret=1
 grep "origin = ns1.example" nslookup.out${n} > /dev/null || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
-status=`expr $status + $ret`
+status=$((status+ret))
 
-n=`expr $n + 1`
-echo_i "Check A only lookup"
+n=$((n+1))
+echo_i "Check A only lookup ($n)"
 ret=0
-$NSLOOKUP -port=${PORT} a-only.example.net 10.53.0.1 > nslookup.out${n} || ret=1
-lines=`grep "Server:" nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
-lines=`grep a-only.example.net nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
+$NSLOOKUP -port=${PORT} a-only.example.net 10.53.0.1 2> nslookup.err${n} > nslookup.out${n} || ret=1
+lines=$(wc -l < nslookup.err${n})
+test $lines -eq 0 || ret=1
+lines=$(grep -c "Server:" nslookup.out${n})
+test $lines -eq 1 || ret=1
+lines=$(grep -c a-only.example.net nslookup.out${n})
+test $lines -eq 1 || ret=1
 grep "1.2.3.4" nslookup.out${n} > /dev/null || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
-status=`expr $status + $ret`
+status=$((status+ret))
 
-n=`expr $n + 1`
-echo_i "Check AAAA only lookup"
+n=$((n+1))
+echo_i "Check AAAA only lookup ($n)"
 ret=0
-$NSLOOKUP -port=${PORT} aaaa-only.example.net 10.53.0.1 > nslookup.out${n} || ret=1
-lines=`grep "Server:" nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
-lines=`grep aaaa-only.example.net nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
+$NSLOOKUP -port=${PORT} aaaa-only.example.net 10.53.0.1 2> nslookup.err${n} > nslookup.out${n} || ret=1
+lines=$(wc -l < nslookup.err${n})
+test $lines -eq 0 || ret=1
+lines=$(grep -c "Server:" nslookup.out${n})
+test $lines -eq 1 || ret=1
+lines=$(grep -c aaaa-only.example.net nslookup.out${n})
+test $lines -eq 1 || ret=1
 grep "2001::ffff" nslookup.out${n} > /dev/null || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
-status=`expr $status + $ret`
+status=$((status+ret))
 
-n=`expr $n + 1`
-echo_i "Check dual A + AAAA lookup"
+n=$((n+1))
+echo_i "Check dual A + AAAA lookup ($n)"
 ret=0
-$NSLOOKUP -port=${PORT} dual.example.net 10.53.0.1 > nslookup.out${n} || ret=1
-lines=`grep "Server:" nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
-lines=`grep dual.example.net nslookup.out${n} | wc -l`
-test $lines = 2 || ret=1
+$NSLOOKUP -port=${PORT} dual.example.net 10.53.0.1 2> nslookup.err${n} > nslookup.out${n} || ret=1
+lines=$(wc -l < nslookup.err${n})
+test $lines -eq 0 || ret=1
+lines=$(grep -c "Server:" nslookup.out${n})
+test $lines -eq 1 || ret=1
+lines=$(grep -c dual.example.net nslookup.out${n})
+test $lines -eq 2 || ret=1
 grep "1.2.3.4" nslookup.out${n} > /dev/null || ret=1
 grep "2001::ffff" nslookup.out${n} > /dev/null || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
-status=`expr $status + $ret`
+status=$((status+ret))
 
-n=`expr $n + 1`
-echo_i "Check CNAME to A only lookup"
+n=$((n+1))
+echo_i "Check CNAME to A only lookup ($n)"
 ret=0
-$NSLOOKUP -port=${PORT} cname-a-only.example.net 10.53.0.1 > nslookup.out${n} || ret=1
-lines=`grep "Server:" nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
-lines=`grep "canonical name" nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
-lines=`grep a-only.example.net nslookup.out${n} | grep -v "canonical name" | wc -l`
-test $lines = 1 || ret=1
+$NSLOOKUP -port=${PORT} cname-a-only.example.net 10.53.0.1 2> nslookup.err${n} > nslookup.out${n} || ret=1
+lines=$(wc -l < nslookup.err${n})
+test $lines -eq 0 || ret=1
+lines=$(grep -c "Server:" nslookup.out${n})
+test $lines -eq 1 || ret=1
+lines=$(grep -c "canonical name" nslookup.out${n})
+test $lines -eq 1 || ret=1
+lines=$(grep a-only.example.net nslookup.out${n} | grep -cv "canonical name")
+test $lines -eq 1 || ret=1
 grep "1.2.3.4" nslookup.out${n} > /dev/null || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
-status=`expr $status + $ret`
+status=$((status+ret))
 
-n=`expr $n + 1`
-echo_i "Check CNAME to AAAA only lookup"
+n=$((n+1))
+echo_i "Check CNAME to AAAA only lookup ($n)"
 ret=0
-$NSLOOKUP -port=${PORT} cname-aaaa-only.example.net 10.53.0.1 > nslookup.out${n} || ret=1
-lines=`grep "Server:" nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
-lines=`grep "canonical name" nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
-lines=`grep aaaa-only.example.net nslookup.out${n} | grep -v "canonical name" |wc -l`
-test $lines = 1 || ret=1
+$NSLOOKUP -port=${PORT} cname-aaaa-only.example.net 10.53.0.1 2> nslookup.err${n} > nslookup.out${n} || ret=1
+lines=$(wc -l < nslookup.err${n})
+test $lines -eq 0 || ret=1
+lines=$(grep -c "Server:" nslookup.out${n})
+test $lines -eq 1 || ret=1
+lines=$(grep -c "canonical name" nslookup.out${n})
+test $lines -eq 1 || ret=1
+lines=$(grep aaaa-only.example.net nslookup.out${n} | grep -cv "canonical name")
+test $lines -eq 1 || ret=1
 grep "2001::ffff" nslookup.out${n} > /dev/null || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
-status=`expr $status + $ret`
+status=$((status+ret))
 
-n=`expr $n + 1`
-echo_i "Check CNAME to dual A + AAAA lookup"
+n=$((n+1))
+echo_i "Check CNAME to dual A + AAAA lookup ($n)"
 ret=0
-$NSLOOKUP -port=${PORT} cname-dual.example.net 10.53.0.1 > nslookup.out${n} || ret=1
-lines=`grep "Server:" nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
-lines=`grep "canonical name" nslookup.out${n} | wc -l`
-test $lines = 1 || ret=1
-lines=`grep dual.example.net nslookup.out${n} | grep -v "canonical name" | wc -l`
-test $lines = 2 || ret=1
+$NSLOOKUP -port=${PORT} cname-dual.example.net 10.53.0.1 2> nslookup.err${n} > nslookup.out${n} || ret=1
+lines=$(wc -l < nslookup.err${n})
+test $lines -eq 0 || ret=1
+lines=$(grep -c "Server:" nslookup.out${n})
+test $lines -eq 1 || ret=1
+lines=$(grep -c "canonical name" nslookup.out${n})
+test $lines -eq 1 || ret=1
+lines=$(grep dual.example.net nslookup.out${n} | grep -cv "canonical name")
+test $lines -eq 2 || ret=1
 grep "1.2.3.4" nslookup.out${n} > /dev/null || ret=1
 grep "2001::ffff" nslookup.out${n} > /dev/null || ret=1
 if [ $ret != 0 ]; then echo_i "failed"; fi
-status=`expr $status + $ret`
+status=$((status+ret))
 
 echo_i "exit status: $status"
 [ $status -eq 0 ] || exit 1