diff --git a/lib/dns/tests/rbt_test.c b/lib/dns/tests/rbt_test.c
index 734238daa1..c38d6783d9 100644
--- a/lib/dns/tests/rbt_test.c
+++ b/lib/dns/tests/rbt_test.c
@@ -167,11 +167,13 @@ test_context_setup(void) {
 		name = dns_fixedname_name(&fname);
 
 		n = isc_mem_get(mctx, sizeof(size_t));
+		ATF_REQUIRE(n != NULL);
 		*n = i + 1;
 		result = dns_rbt_addname(ctx->rbt, name, n);
 		ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
 
 		n = isc_mem_get(mctx, sizeof(size_t));
+		ATF_REQUIRE(n != NULL);
 		*n = node_distances[i];
 		result = dns_rbt_addname(ctx->rbt_distances, name, n);
 		ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
@@ -364,6 +366,7 @@ ATF_TC_BODY(rbt_check_distance_random, tc) {
 		char namebuf[34];
 
 		n = isc_mem_get(mctx, sizeof(size_t));
+		ATF_REQUIRE(n != NULL);
 		*n = i + 1;
 
 		while (1) {
@@ -450,6 +453,7 @@ ATF_TC_BODY(rbt_check_distance_ordered, tc) {
 		dns_name_t *name;
 
 		n = isc_mem_get(mctx, sizeof(size_t));
+		ATF_REQUIRE(n != NULL);
 		*n = i + 1;
 
 		snprintf(namebuf, sizeof(namebuf), "name%08x.", i);
@@ -736,6 +740,7 @@ ATF_TC_BODY(rbt_remove, tc) {
 			ATF_REQUIRE_EQ(node->data, NULL);
 
 			n = isc_mem_get(mctx, sizeof(size_t));
+			ATF_REQUIRE(n != NULL);
 			*n = i;
 
 			node->data = n;
@@ -1144,6 +1149,7 @@ ATF_TC_BODY(rbt_addname, tc) {
 	ctx = test_context_setup();
 
 	n = isc_mem_get(mctx, sizeof(size_t));
+	ATF_REQUIRE(n != NULL);
 	*n = 1;
 
 	dns_test_namefromstring("d.e.f.g.h.i.j.k", &fname);
@@ -1155,6 +1161,7 @@ ATF_TC_BODY(rbt_addname, tc) {
 
 	/* Now add again, should get ISC_R_EXISTS */
 	n = isc_mem_get(mctx, sizeof(size_t));
+	ATF_REQUIRE(n != NULL);
 	*n = 2;
 	result = dns_rbt_addname(ctx->rbt, name, n);
 	ATF_REQUIRE_EQ(result, ISC_R_EXISTS);