diff --git a/src/video/vid_svga.c b/src/video/vid_svga.c
index 307f455c3..5d579585a 100644
--- a/src/video/vid_svga.c
+++ b/src/video/vid_svga.c
@@ -1343,7 +1343,7 @@ svga_init(const device_t *info, svga_t *svga, void *priv, int memsize,
     svga->vram_max          = memsize;
     svga->vram_display_mask = svga->vram_mask = memsize - 1;
     svga->decode_mask                         = 0x7fffff;
-    svga->changedvram                         = calloc(memsize >> 12, 1);
+    svga->changedvram                         = calloc((memsize >> 12) + 1, 1);
     svga->recalctimings_ex                    = recalctimings_ex;
     svga->video_in                            = video_in;
     svga->video_out                           = video_out;