diff --git a/tools/testing/selftests/kvm/s390x/resets.c b/tools/testing/selftests/kvm/s390x/resets.c
index c59db2c95e9e3c513d7302edae6e592db80b8cf3..bf04d77de16b52d4eba50cbd6e1fa019f62707df 100644
--- a/tools/testing/selftests/kvm/s390x/resets.c
+++ b/tools/testing/selftests/kvm/s390x/resets.c
@@ -53,7 +53,7 @@ static void test_one_reg(uint64_t id, uint64_t value)
 	reg.addr = (uintptr_t)&eval_reg;
 	reg.id = id;
 	vcpu_get_reg(vm, VCPU_ID, &reg);
-	TEST_ASSERT(eval_reg == value, "value == %s", value);
+	TEST_ASSERT(eval_reg == value, "value == 0x%lx", value);
 }
 
 static void assert_noirq(void)