diff --git a/src/settings_type.h b/src/settings_type.h
--- a/src/settings_type.h
+++ b/src/settings_type.h
@@ -115,6 +115,7 @@ struct GUISettings {
 	bool   expenses_layout;                  ///< layout of expenses window
 	uint32 last_newgrf_count;                ///< the numbers of NewGRFs we found during the last scan
 	byte   missing_strings_threshold;        ///< the number of missing strings before showing the warning
+	uint8  graph_line_thickness;             ///< the thickness of the lines in the various graph guis
 
 	uint16 console_backlog_timeout;          ///< the minimum amount of time items should be in the console backlog before they will be removed in ~3 seconds granularity.
 	uint16 console_backlog_length;           ///< the minimum amount of items in the console backlog before items will be removed.