diff --git a/src/vid_ati_mach64.c b/src/vid_ati_mach64.c
index 0b7a58f..d746b0c 100644
--- a/src/vid_ati_mach64.c
+++ b/src/vid_ati_mach64.c
@@ -416,6 +416,7 @@ void mach64_recalctimings(svga_t *svga)
                 svga->linedbl = svga->rowcount = 0;
                 svga->split = 0xffffff;
                 svga->vblankstart = svga->dispend;
+                svga->rowcount = mach64->crtc_gen_cntl & 1;
 //                svga_htotal <<= 1;
 //                svga_hdisp <<= 1;
                 svga->rowoffset <<= 1;