diff --git a/hw/display/ati.c b/hw/display/ati.c
index 245130d52f..95fc443cac 100644
--- a/hw/display/ati.c
+++ b/hw/display/ati.c
@@ -86,8 +86,8 @@ static void ati_vga_switch_mode(ATIVGAState *s)
                 break;
             default:
                 qemu_log_mask(LOG_UNIMP, "Unsupported bpp value\n");
+                return;
             }
-            assert(bpp != 0);
             DPRINTF("Switching to %dx%d %d %d @ %x\n", h, v, stride, bpp, offs);
             vbe_ioport_write_index(&s->vga, 0, VBE_DISPI_INDEX_ENABLE);
             vbe_ioport_write_data(&s->vga, 0, VBE_DISPI_DISABLED);