diff --git a/components/spiffs/test/test_spiffs.c b/components/spiffs/test/test_spiffs.c
index 60bca410bd..cb2164ac1f 100644
--- a/components/spiffs/test/test_spiffs.c
+++ b/components/spiffs/test/test_spiffs.c
@@ -291,7 +291,8 @@ void test_spiffs_readdir_many_files(const char* dir_prefix)
             if (!de) {
                 break;
             }
-            snprintf(file_name, sizeof(file_name), "%s/%s", dir_prefix, de->d_name);
+            int len = snprintf(file_name, sizeof(file_name), "%s/%s", dir_prefix, de->d_name);
+            assert(len < sizeof(file_name));
             unlink(file_name);
         }
     }