diff --git a/hw/qdev.c b/hw/qdev.c
index c242097..fe4de96 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -76,6 +76,27 @@ void qemu_devices_reset(void)
     }
 }
 
+/* vmstate register/unregister:
+ *
+ * The real implementations are on qdev-system.c and savevm.c.
+ * Those are weak symbols used by *-user.
+ */
+
+GCC_WEAK int vmstate_register_with_alias_id(DeviceState *dev,
+                                            int instance_id,
+                                            const VMStateDescription *vmsd,
+                                            void *base, int alias_id,
+                                            int required_for_version)
+{
+    return 0;
+}
+
+GCC_WEAK void vmstate_unregister(DeviceState *dev,
+                                 const VMStateDescription *vmsd,
+                                 void *opaque)
+{
+}
+
 const VMStateDescription *qdev_get_vmsd(DeviceState *dev)
 {
     DeviceClass *dc = DEVICE_GET_CLASS(dev);
diff --git a/vmstate.h b/vmstate.h
index 623af0a..7a56b88 100644
--- a/vmstate.h
+++ b/vmstate.h
@@ -624,11 +624,13 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                         void *opaque);
 int vmstate_register(DeviceState *dev, int instance_id,
                      const VMStateDescription *vmsd, void *base);
-int vmstate_register_with_alias_id(DeviceState *dev, int instance_id,
+
+/* The following functions have GCC_WEAK stubs on qdev-core, for *-user: */
+GCC_WEAK_DECL int vmstate_register_with_alias_id(DeviceState *dev, int instance_id,
                                    const VMStateDescription *vmsd,
                                    void *base, int alias_id,
                                    int required_for_version);
-void vmstate_unregister(DeviceState *dev, const VMStateDescription *vmsd,
+GCC_WEAK_DECL void vmstate_unregister(DeviceState *dev, const VMStateDescription *vmsd,
                         void *opaque);
 
 struct MemoryRegion;