diff --git a/block.c b/block.c
index 49dd6bb..8739635 100644
--- a/block.c
+++ b/block.c
@@ -787,7 +787,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
               BlockDriver *drv)
 {
     int ret;
-    char tmp_filename[PATH_MAX];
+    char tmp_filename[PATH_MAX + 1];
 
     if (flags & BDRV_O_SNAPSHOT) {
         BlockDriverState *bs1;