diff --git a/src/video/vid_ati_mach64.c b/src/video/vid_ati_mach64.c
index ed554309b..0d816ba7f 100644
--- a/src/video/vid_ati_mach64.c
+++ b/src/video/vid_ati_mach64.c
@@ -2282,6 +2282,7 @@ void mach64_ext_writeb(uint32_t addr, uint8_t val, void *p)
                         svga->fb_only = 1;
                 else
                         svga->fb_only = 0;
+                svga->dpms = !!(mach64->crtc_gen_cntl & 0x0c);
                 svga_recalctimings(&mach64->svga);
                 break;