diff --git a/src/vid_sdac_ramdac.c b/src/vid_sdac_ramdac.c
index 0098d60..c02eed4 100644
--- a/src/vid_sdac_ramdac.c
+++ b/src/vid_sdac_ramdac.c
@@ -50,8 +50,8 @@ void sdac_ramdac_out(uint16_t addr, uint8_t val, sdac_ramdac_t *ramdac, svga_t *
                 ramdac->magic_count = 0;
                 if (ramdac->rs2)
                 {
-                        if (!ramdac->reg_ff) ramdac->regs[ramdac->windex] = (ramdac->regs[ramdac->windex] & 0xff00) | val;
-                        else                 ramdac->regs[ramdac->windex] = (ramdac->regs[ramdac->windex] & 0x00ff) | (val << 8);
+                        if (!ramdac->reg_ff) ramdac->regs[ramdac->windex & 0xff] = (ramdac->regs[ramdac->windex & 0xff] & 0xff00) | val;
+                        else                 ramdac->regs[ramdac->windex & 0xff] = (ramdac->regs[ramdac->windex & 0xff] & 0x00ff) | (val << 8);
                         ramdac->reg_ff = !ramdac->reg_ff;
 //                        pclog("RAMDAC reg %02X now %04X\n", ramdac->windex, ramdac->regs[ramdac->windex]);
                         if (!ramdac->reg_ff) ramdac->windex++;
@@ -106,8 +106,8 @@ uint8_t sdac_ramdac_in(uint16_t addr, sdac_ramdac_t *ramdac, svga_t *svga)
 //                }
                 if (ramdac->rs2)
                 {
-                        if (!ramdac->reg_ff) temp = ramdac->regs[ramdac->rindex] & 0xff;
-                        else                 temp = ramdac->regs[ramdac->rindex] >> 8;
+                        if (!ramdac->reg_ff) temp = ramdac->regs[ramdac->rindex & 0xff] & 0xff;
+                        else                 temp = ramdac->regs[ramdac->rindex & 0xff] >> 8;
                         ramdac->reg_ff = !ramdac->reg_ff;
                         if (!ramdac->reg_ff)
                         {