diff --git a/hw/qxl.c b/hw/qxl.c
index db2318e293..c3540c3d50 100644
--- a/hw/qxl.c
+++ b/hw/qxl.c
@@ -1370,7 +1370,7 @@ async_common:
     case QXL_IO_DESTROY_SURFACE_WAIT:
         if (val >= NUM_SURFACES) {
             qxl_guest_bug(d, "QXL_IO_DESTROY_SURFACE (async=%d):"
-                             "%d >= NUM_SURFACES", async, val);
+                             "%" PRIu64 " >= NUM_SURFACES", async, val);
             goto cancel_async;
         }
         qxl_spice_destroy_surface_wait(d, val, async);
diff --git a/hw/qxl.h b/hw/qxl.h
index 11a0db3f7d..cbb1e2d6d4 100644
--- a/hw/qxl.h
+++ b/hw/qxl.h
@@ -127,7 +127,7 @@ typedef struct PCIQXLDevice {
 
 /* qxl.c */
 void *qxl_phys2virt(PCIQXLDevice *qxl, QXLPHYSICAL phys, int group_id);
-void qxl_guest_bug(PCIQXLDevice *qxl, const char *msg, ...);
+void qxl_guest_bug(PCIQXLDevice *qxl, const char *msg, ...) GCC_FMT_ATTR(2, 3);
 
 void qxl_spice_update_area(PCIQXLDevice *qxl, uint32_t surface_id,
                            struct QXLRect *area, struct QXLRect *dirty_rects,