diff --git a/src/video/vid_s3_virge.c b/src/video/vid_s3_virge.c
index dcf380ff8..e9da4b412 100644
--- a/src/video/vid_s3_virge.c
+++ b/src/video/vid_s3_virge.c
@@ -1975,9 +1975,9 @@ s3_virge_mmio_write_l(uint32_t addr, uint32_t val, void *priv)
                 break;
             case 0x8190:
                 virge->streams.sec_ctrl              = val;
-                virge->streams.dda_horiz_accumulator = val & 0xfff;
-                if (val & 0x1000)
-                    virge->streams.dda_horiz_accumulator |= ~0xfff;
+                virge->streams.dda_horiz_accumulator = val & 0x7ff;
+                if (val & 0x800)
+                    virge->streams.dda_horiz_accumulator |= ~0x7ff;
 
                 virge->streams.sdif = (val >> 24) & 7;
                 break;
@@ -1990,9 +1990,9 @@ s3_virge_mmio_write_l(uint32_t addr, uint32_t val, void *priv)
                 if (val & 0x800)
                     virge->streams.k1_horiz_scale |= ~0x7ff;
 
-                virge->streams.k2_horiz_scale = (val >> 16) & 0x7ff;
-                if ((val >> 16) & 0x800)
-                    virge->streams.k2_horiz_scale |= ~0x7ff;
+                virge->streams.k2_horiz_scale = (val >> 16) & 0x3ff;
+                if ((val >> 16) & 0x400)
+                    virge->streams.k2_horiz_scale |= ~0x3ff;
 
                 svga_recalctimings(svga);
                 svga->fullchange = changeframecount;
@@ -2048,14 +2048,14 @@ s3_virge_mmio_write_l(uint32_t addr, uint32_t val, void *priv)
                     virge->streams.k1_vert_scale |= ~0x7ff;
                 break;
             case 0x81e4:
-                virge->streams.k2_vert_scale = val & 0x7ff;
-                if (val & 0x800)
-                    virge->streams.k2_vert_scale |= ~0x7ff;
+                virge->streams.k2_vert_scale = val & 0x3ff;
+                if (val & 0x400)
+                    virge->streams.k2_vert_scale |= ~0x3ff;
                 break;
             case 0x81e8:
-                virge->streams.dda_vert_accumulator = val & 0xfff;
-                if (val & 0x1000)
-                    virge->streams.dda_vert_accumulator |= ~0xfff;
+                virge->streams.dda_vert_accumulator = val & 0x7ff;
+                if (val & 0x800)
+                    virge->streams.dda_vert_accumulator |= ~0x7ff;
 
                 svga_recalctimings(svga);
                 svga->fullchange = changeframecount;