diff --git a/fs/squashfs/xz_wrapper.c b/fs/squashfs/xz_wrapper.c
index 0a4ff3ec9c8c..6610af241449 100644
--- a/fs/squashfs/xz_wrapper.c
+++ b/fs/squashfs/xz_wrapper.c
@@ -57,10 +57,10 @@ static void *squashfs_xz_comp_opts(struct squashfs_sb_info *msblk,
 
 		opts->dict_size = le32_to_cpu(comp_opts->dictionary_size);
 
-		/* the dictionary size should be 2^n or 2^n+2^(n+1) */
+		/* the dictionary size should be positive and 2^n or 2^n+2^(n+1) */
 		n = ffs(opts->dict_size) - 1;
-		if (opts->dict_size != (1 << n) && opts->dict_size != (1 << n) +
-						(1 << (n + 1))) {
+		if (opts->dict_size <= 0 || (opts->dict_size != (1 << n) &&
+			opts->dict_size != (1 << n) + (1 << (n + 1)))) {
 			err = -EIO;
 			goto out;
 		}