diff --git a/bin/tests/system/dnssec/tests.sh b/bin/tests/system/dnssec/tests.sh
index 09c8be1250..8616733942 100644
--- a/bin/tests/system/dnssec/tests.sh
+++ b/bin/tests/system/dnssec/tests.sh
@@ -2191,7 +2191,7 @@ echo_i "checking RRSIG query from cache ($n)"
 ret=0
 dig_with_opts normalthenrrsig.secure.example. @10.53.0.4 a >/dev/null || ret=1
 ans=$(dig_with_opts +short normalthenrrsig.secure.example. @10.53.0.4 rrsig) || ret=1
-expect=$(dig_with_opts +short normalthenrrsig.secure.example. @10.53.0.3 rrsig | grep '^\(A\|NSEC\)') || ret=1
+expect=$(dig_with_opts +short normalthenrrsig.secure.example. @10.53.0.3 rrsig | grep -E '^(A|NSEC)') || ret=1
 test "$ans" = "$expect" || ret=1
 # also check that RA is set
 dig_with_opts normalthenrrsig.secure.example. @10.53.0.4 rrsig >dig.out.ns4.test$n || ret=1