diff --git a/tests/libqos/libqos.c b/tests/libqos/libqos.c
index c478bc958c..c8b3ef044b 100644
--- a/tests/libqos/libqos.c
+++ b/tests/libqos/libqos.c
@@ -16,16 +16,13 @@
  * Launch QEMU with the given command line,
  * and then set up interrupts and our guest malloc interface.
  */
-QOSState *qtest_boot(const char *cmdline_fmt, ...)
+QOSState *qtest_vboot(const char *cmdline_fmt, va_list ap)
 {
-    QOSState *qs = g_malloc(sizeof(QOSState));
     char *cmdline;
-    va_list ap;
 
-    va_start(ap, cmdline_fmt);
+    struct QOSState *qs = g_malloc(sizeof(QOSState));
+
     cmdline = g_strdup_vprintf(cmdline_fmt, ap);
-    va_end(ap);
-
     qs->qts = qtest_start(cmdline);
     qtest_irq_intercept_in(global_qtest, "ioapic");
     qs->alloc = pc_alloc_init();
@@ -34,6 +31,22 @@ QOSState *qtest_boot(const char *cmdline_fmt, ...)
     return qs;
 }
 
+/**
+ * Launch QEMU with the given command line,
+ * and then set up interrupts and our guest malloc interface.
+ */
+QOSState *qtest_boot(const char *cmdline_fmt, ...)
+{
+    QOSState *qs;
+    va_list ap;
+
+    va_start(ap, cmdline_fmt);
+    qs = qtest_vboot(cmdline_fmt, ap);
+    va_end(ap);
+
+    return qs;
+}
+
 /**
  * Tear down the QEMU instance.
  */
diff --git a/tests/libqos/libqos.h b/tests/libqos/libqos.h
index 7a106f24e9..7ae0a8d600 100644
--- a/tests/libqos/libqos.h
+++ b/tests/libqos/libqos.h
@@ -10,6 +10,7 @@ typedef struct QOSState {
     QGuestAllocator *alloc;
 } QOSState;
 
+QOSState *qtest_vboot(const char *cmdline_fmt, va_list ap);
 QOSState *qtest_boot(const char *cmdline_fmt, ...);
 void qtest_shutdown(QOSState *qs);