diff --git a/variables.h b/variables.h
index 5e0dda8acf..bfabba4cf4 100644
--- a/variables.h
+++ b/variables.h
@@ -170,8 +170,8 @@ typedef struct Patches {
 	byte wait_oneway_signal;	//waitingtime in days before a oneway signal
 	byte wait_twoway_signal;	//waitingtime in days before a twoway signal
 
-	uint map_x; // Size of map
-	uint map_y;
+	uint8 map_x; // Size of map
+	uint8 map_y;
 
 	byte drag_signals_density; // many signals density
 	bool ainew_active;  // Is the new AI active?