diff --git a/lib/hypervisor/hv_kvm.py b/lib/hypervisor/hv_kvm.py
index 59994cd29cbbe777d78986a99082e7cdedf3d50f..c680cf421f4083409a2272452e99c60334a35ae7 100644
--- a/lib/hypervisor/hv_kvm.py
+++ b/lib/hypervisor/hv_kvm.py
@@ -962,6 +962,7 @@ class KVMHypervisor(hv_base.BaseHypervisor):
     kvm_cmd.extend(["-m", instance.beparams[constants.BE_MAXMEM]])
     kvm_cmd.extend(["-smp", instance.beparams[constants.BE_VCPUS]])
     kvm_cmd.extend(["-pidfile", pidfile])
+    kvm_cmd.extend(["-balloon", "virtio"])
     kvm_cmd.extend(["-daemonize"])
     if not instance.hvparams[constants.HV_ACPI]:
       kvm_cmd.extend(["-no-acpi"])