diff --git a/src/video/vid_s3.c b/src/video/vid_s3.c
index 14728bac8..ad7e77aa7 100644
--- a/src/video/vid_s3.c
+++ b/src/video/vid_s3.c
@@ -3273,10 +3273,8 @@ s3_recalctimings(svga_t *svga)
             svga->dots_per_clock = ((svga->seqregs[1] & 1) ? 16 : 18);
         }
 
-        svga->hblankstart    = (((svga->crtc[0x5d] & 0x10) >> 4) << 8) + svga->crtc[2] + 1;
+        svga->hblankstart    = (((svga->crtc[0x5d] & 0x04) >> 2) << 8) + svga->crtc[2] + 1;
 
-        if (svga->crtc[0x5d] & 0x04)
-            svga->hblankstart += 0x100;
         if (s3->chip >= S3_VISION964) {
             /* NOTE: The S3 Trio64V+ datasheet says this is bit 7, but then where is bit 6?
                      The datasheets for the pre-Trio64V+ cards say +64, which implies bit 6,
@@ -4191,7 +4189,7 @@ s3_trio64v_recalctimings(svga_t *svga)
         /* Also make sure vertical blanking starts on display end. */
         svga->vblankstart = svga->dispend;
     } else {
-        svga->hblankstart    = (((svga->crtc[0x5d] & 0x10) >> 4) << 8) + svga->crtc[2] + 1;
+        svga->hblankstart    = (((svga->crtc[0x5d] & 0x04) >> 2) << 8) + svga->crtc[2] + 1;
 
         /* NOTE: The S3 Trio64V+ datasheet says this is bit 7, but then where is bit 6?
                  The datasheets for the pre-Trio64V+ cards say +64, which implies bit 6,