diff --git a/simtool.h b/simtool.h
index 287639c1a..a9bb98707 100644
--- a/simtool.h
+++ b/simtool.h
@@ -35,6 +35,7 @@ class way_obj_desc_t;
 /****************************** helper functions: *****************************/
 
 char *tooltip_with_price(const char * tip, sint64 price);
+char *tooltip_with_price_length(const char * tip, sint64 price, sint64 length);
 
 void open_error_msg_win(const char* error);