diff --git a/tools/testing/selftests/net/forwarding/mirror_gre_bridge_1d_vlan.sh b/tools/testing/selftests/net/forwarding/mirror_gre_bridge_1d_vlan.sh
index 197e769c2ed1..f8cda822c1ce 100755
--- a/tools/testing/selftests/net/forwarding/mirror_gre_bridge_1d_vlan.sh
+++ b/tools/testing/selftests/net/forwarding/mirror_gre_bridge_1d_vlan.sh
@@ -86,11 +86,20 @@ test_ip6gretap()
 
 test_gretap_stp()
 {
+	# Sometimes after mirror installation, the neighbor's state is not valid.
+	# The reason is that there is no SW datapath activity related to the
+	# neighbor for the remote GRE address. Therefore whether the corresponding
+	# neighbor will be valid is a matter of luck, and the test is thus racy.
+	# Set the neighbor's state to permanent, so it would be always valid.
+	ip neigh replace 192.0.2.130 lladdr $(mac_get $h3) \
+		nud permanent dev br2
 	full_test_span_gre_stp gt4 $swp3.555 "mirror to gretap"
 }
 
 test_ip6gretap_stp()
 {
+	ip neigh replace 2001:db8:2::2 lladdr $(mac_get $h3) \
+		nud permanent dev br2
 	full_test_span_gre_stp gt6 $swp3.555 "mirror to ip6gretap"
 }