diff --git a/dbus.c b/dbus.c
index 96527ac8cf..e2f8f3cd49 100644
--- a/dbus.c
+++ b/dbus.c
@@ -697,7 +697,7 @@ DBusHandlerResult bus_default_message_handler(Manager *m, DBusMessage *message,
                         if (!dbus_message_iter_open_container(&iter, DBUS_TYPE_VARIANT, p->signature, &sub))
                                 goto oom;
 
-                        if ((r = p->append(m, &sub, property, p->data)) < 0) {
+                        if ((r = p->append(m, &sub, property, (void*) p->data)) < 0) {
 
                                 if (r == -ENOMEM)
                                         goto oom;
@@ -739,7 +739,7 @@ DBusHandlerResult bus_default_message_handler(Manager *m, DBusMessage *message,
                             !dbus_message_iter_open_container(&sub2, DBUS_TYPE_VARIANT, p->signature, &sub3))
                                 goto oom;
 
-                        if ((r = p->append(m, &sub3, p->property, p->data)) < 0) {
+                        if ((r = p->append(m, &sub3, p->property, (void*) p->data)) < 0) {
 
                                 if (r == -ENOMEM)
                                         goto oom;
diff --git a/dbus.h b/dbus.h
index 06b7e20602..5b41877e8c 100644
--- a/dbus.h
+++ b/dbus.h
@@ -33,7 +33,7 @@ typedef struct BusProperty {
         const char *property;            /* name of the property */
         BusPropertyCallback append;      /* Function that is called to serialize this property */
         const char *signature;
-        void *data;                      /* The data of this property */
+        const void *data;                /* The data of this property */
 } BusProperty;
 
 #define BUS_PROPERTIES_INTERFACE                                        \