diff --git a/py/objstr.c b/py/objstr.c
index c27b19939..a3f2d6075 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -790,6 +790,8 @@ mp_obj_t str_format(uint n_args, const mp_obj_t *args) {
             }
         }
 
+        // NOTE: no else here. We need the e, f, g etc formats for integer
+        //       arguments (from above if) to take this if.
         if (arg_looks_numeric(arg)) {
             if (!type) {