diff --git a/hw/qxl.c b/hw/qxl.c
index 59bf822..89e9ad9 100644
--- a/hw/qxl.c
+++ b/hw/qxl.c
@@ -1703,7 +1703,7 @@ static void qxl_hw_text_update(void *opaque, console_ch_t *chardata)
 
 static void qxl_dirty_surfaces(PCIQXLDevice *qxl)
 {
-    intptr_t vram_start;
+    uintptr_t vram_start;
     int i;
 
     if (qxl->mode != QXL_MODE_NATIVE && qxl->mode != QXL_MODE_COMPAT) {
@@ -1714,7 +1714,7 @@ static void qxl_dirty_surfaces(PCIQXLDevice *qxl)
     qxl_set_dirty(&qxl->vga.vram, qxl->shadow_rom.draw_area_offset,
                   qxl->shadow_rom.surface0_area_size);
 
-    vram_start =  (intptr_t)memory_region_get_ram_ptr(&qxl->vram_bar);
+    vram_start = (uintptr_t)memory_region_get_ram_ptr(&qxl->vram_bar);
 
     /* dirty the off-screen surfaces */
     for (i = 0; i < NUM_SURFACES; i++) {