diff --git a/lib/dns/tests/nsec3_test.c b/lib/dns/tests/nsec3_test.c
index 51313c1f34..3ba48768c5 100644
--- a/lib/dns/tests/nsec3_test.c
+++ b/lib/dns/tests/nsec3_test.c
@@ -103,19 +103,19 @@ nsec3param_salttotext_test(const nsec3param_salttotext_test_params_t *params) {
 	ATF_CHECK_EQ_MSG(result, ISC_R_NOSPACE,
 			 "\"%s\": expected a %lu-byte target buffer to be "
 			 "rejected, got %s\n",
-			 params->nsec3param_text, length - 1,
+			 params->nsec3param_text, (unsigned long)(length - 1),
 			 isc_result_totext(result));
 	result = dns_nsec3param_salttotext(&nsec3param, salt, length);
 	ATF_CHECK_EQ_MSG(result, ISC_R_NOSPACE,
 			 "\"%s\": expected a %lu-byte target buffer to be "
 			 "rejected, got %s\n",
-			 params->nsec3param_text, length,
+			 params->nsec3param_text, (unsigned long)length,
 			 isc_result_totext(result));
 	result = dns_nsec3param_salttotext(&nsec3param, salt, length + 1);
 	ATF_CHECK_EQ_MSG(result, ISC_R_SUCCESS,
 			 "\"%s\": expected a %lu-byte target buffer to be "
 			 "accepted, got %s\n",
-			 params->nsec3param_text, length + 1,
+			 params->nsec3param_text, (unsigned long)(length + 1),
 			 isc_result_totext(result));
 }
 
diff --git a/lib/dns/tests/rdata_test.c b/lib/dns/tests/rdata_test.c
index 8fabf522f3..7a2f87af26 100644
--- a/lib/dns/tests/rdata_test.c
+++ b/lib/dns/tests/rdata_test.c
@@ -239,7 +239,7 @@ check_wire_ok_single(const wire_ok_t *wire_ok, dns_rdataclass_t rdclass,
 				   wire_ok->lineno,
 				   dns_test_tohex(wire_ok->data, wire_ok->len,
 						  hex, sizeof(hex)),
-				   wire_ok->len);
+				   (unsigned long)wire_ok->len);
 	} else {
 		ATF_REQUIRE_MSG(result != ISC_R_SUCCESS,
 				"line %d: %s (%lu): "
@@ -247,7 +247,7 @@ check_wire_ok_single(const wire_ok_t *wire_ok, dns_rdataclass_t rdclass,
 				wire_ok->lineno,
 				dns_test_tohex(wire_ok->data, wire_ok->len,
 					       hex, sizeof(hex)),
-				wire_ok->len);
+				(unsigned long)wire_ok->len);
 	}
 	/*
 	 * If data was parsed correctly, perform two-way conversion checks