diff --git a/sw/tools/gen_settings.ml b/sw/tools/gen_settings.ml
index b3c045df86..8d2042dc9e 100644
--- a/sw/tools/gen_settings.ml
+++ b/sw/tools/gen_settings.ml
@@ -216,9 +216,9 @@ let parse_rc_setting = fun xml ->
   let t = (ExtXml.attrib xml "type") in
   let param_macro = param_macro_of_type t in
   let dot_pos =
-    try String.rindex var '.' with
+    try String.rindex var '.' + 1 with
       Not_found -> 0 in
-  let var_nostruct = String.sub var (String.length var - dot_pos) dot_pos in
+  let var_nostruct = String.sub var dot_pos (String.length var - dot_pos) in
   let var_init = var_nostruct ^ "_init" in
 
   lprintf "if (rc_settings_mode == RC_SETTINGS_MODE_%s) { \\\n" (String.uppercase cm);