diff --git a/src/VIDEO/vid_s3.c b/src/VIDEO/vid_s3.c
index 6cc18d7e9..c9691cf5d 100644
--- a/src/VIDEO/vid_s3.c
+++ b/src/VIDEO/vid_s3.c
@@ -792,8 +792,15 @@ void s3_out(uint16_t addr, uint8_t val, void *p)
                 break;
                 
                 case 0x3C6: case 0x3C7: case 0x3C8: case 0x3C9:
-                sdac_ramdac_out(addr, val, &s3->ramdac, svga);
-                return;
+		if (s3->chip == S3_VISION864)
+		{
+	                sdac_ramdac_out(addr, val, &s3->ramdac, svga);
+        	        return;
+		}
+		else
+		{
+			break;
+		}
 
                 case 0x3D4:
                 svga->crtcreg = val & 0x7f;
@@ -930,7 +937,14 @@ uint8_t s3_in(uint16_t addr, void *p)
                 break;
                 
                 case 0x3c6: case 0x3c7: case 0x3c8: case 0x3c9:
-                return sdac_ramdac_in(addr, &s3->ramdac, svga);
+		if (s3->chip == S3_VISION864)
+		{
+	                return sdac_ramdac_in(addr, &s3->ramdac, svga);
+		}
+		else
+		{
+			break;
+		}
 
                 case 0x3d4:
                 return svga->crtcreg;