diff --git a/tests/unittests/tests-spiffs/tests-spiffs.c b/tests/unittests/tests-spiffs/tests-spiffs.c
index d2b2ae5fad..c781f15b6f 100644
--- a/tests/unittests/tests-spiffs/tests-spiffs.c
+++ b/tests/unittests/tests-spiffs/tests-spiffs.c
@@ -145,6 +145,31 @@ static void test_spiffs_teardown(void)
     vfs_umount(&_test_spiffs_mount);
 }
 
+static void tests_spiffs_format(void)
+{
+    int res;
+    vfs_umount(&_test_spiffs_mount);
+    res = mtd_erase(_dev, 0, _dev->page_size * _dev->pages_per_sector * _dev->sector_count);
+    TEST_ASSERT_EQUAL_INT(0, res);
+
+    res = vfs_mount(&_test_spiffs_mount);
+    TEST_ASSERT(res < 0);
+
+    /* 1. format an invalid file system (failed mount) */
+    res = vfs_format(&_test_spiffs_mount);
+    TEST_ASSERT_EQUAL_INT(0, res);
+
+    res = vfs_mount(&_test_spiffs_mount);
+    TEST_ASSERT_EQUAL_INT(0, res);
+
+    res = vfs_umount(&_test_spiffs_mount);
+    TEST_ASSERT_EQUAL_INT(0, res);
+
+    /* 2. format a valid file system */
+    res = vfs_format(&_test_spiffs_mount);
+    TEST_ASSERT_EQUAL_INT(0, res);
+}
+
 static void tests_spiffs_mount_umount(void)
 {
     int res;
@@ -360,6 +385,7 @@ static void tests_spiffs_statvfs(void)
 Test *tests_spiffs_tests(void)
 {
     EMB_UNIT_TESTFIXTURES(fixtures) {
+        new_TestFixture(tests_spiffs_format),
         new_TestFixture(tests_spiffs_mount_umount),
         new_TestFixture(tests_spiffs_open_close),
         new_TestFixture(tests_spiffs_write),