diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index f38d04f663dd1f22fcd40b3825a2cda410c638f3..c94d2ef4b898bc98cec8a7029a52651d738b0629 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -5443,7 +5443,7 @@ qemuMonitorJSONGetCPUModelExpansion(qemuMonitorPtr mon,
     if (VIR_STRDUP(machine_model->name, cpu_name) < 0)
         goto cleanup;
 
-    if (VIR_ALLOC_N(machine_model->props, cpu_props->data.object.npairs) < 0)
+    if (VIR_ALLOC_N(machine_model->props, virJSONValueObjectKeysNumber(cpu_props)) < 0)
         goto cleanup;
 
     if (virJSONValueObjectForeachKeyValue(cpu_props,