diff --git a/tests/qtest/numa-test.c b/tests/qtest/numa-test.c
index 2f9b7f6..e1ed6d4 100644
--- a/tests/qtest/numa-test.c
+++ b/tests/qtest/numa-test.c
@@ -455,7 +455,7 @@
     cli = make_cli(data, "-nodefaults --preconfig "
                          "-smp 2,sockets=2 "
                          "-m 128M,slots=2,maxmem=1G "
-                         "-object memory-backend-ram,size=64M,id=m0 "
+                         "-object memory-backend-ram,size=64M,id=m0,prealloc=y "
                          "-object memory-backend-ram,size=64M,id=m1 "
                          "-numa node,nodeid=0,memdev=m0");
     qs = qtest_init(cli);