diff --git a/.github/workflows/c-cpp.yml b/.github/workflows/c-cpp.yml
index ad8e159..aca29fd 100644
--- a/.github/workflows/c-cpp.yml
+++ b/.github/workflows/c-cpp.yml
@@ -37,7 +37,7 @@ jobs:
         sudo mkdir /cores
         sudo cp fsck/fsck.exfat /cores
         cd tests
-        sudo ./test_fsck.sh
+        sudo ./test_fsck.sh bad_root
         sudo coredumpctl list
         sudo chmod -R a+rwx /cores
         sudo coredumpctl dump | gzip -c > /cores/core.gz
diff --git a/fsck/fsck.c b/fsck/fsck.c
index a5517d2..7edb19f 100644
--- a/fsck/fsck.c
+++ b/fsck/fsck.c
@@ -569,14 +569,16 @@ static uint16_t file_calc_checksum(struct exfat_de_iter *iter)
 {
 	uint16_t checksum;
 	struct exfat_dentry *file_de, *de;
-	int i;
+	int i, ret;
 
 	checksum = 0;
 	exfat_de_iter_get(iter, 0, &file_de);
 
 	exfat_calc_dentry_checksum(file_de, &checksum, true);
 	for (i = 1; i <= file_de->file_num_ext; i++) {
-		exfat_de_iter_get(iter, i, &de);
+		ret = exfat_de_iter_get(iter, i, &de);
+		if (ret)
+			return 0;
 		exfat_calc_dentry_checksum(de, &checksum, false);
 	}
 	return checksum;