diff --git a/road.h b/road.h
index 1d8d4b8629..a7860af285 100644
--- a/road.h
+++ b/road.h
@@ -4,10 +4,10 @@
 #define ROAD_H
 
 typedef enum RoadBits {
-	ROAD_NW  = 1,
-	ROAD_SW  = 2,
-	ROAD_SE  = 4,
-	ROAD_NE  = 8,
+	ROAD_NW  = 1U,
+	ROAD_SW  = 2U,
+	ROAD_SE  = 4U,
+	ROAD_NE  = 8U,
 	ROAD_X   = ROAD_SW | ROAD_NE,
 	ROAD_Y   = ROAD_NW | ROAD_SE,
 	ROAD_ALL = ROAD_X  | ROAD_Y
@@ -20,7 +20,7 @@ static inline RoadBits ComplementRoadBits(RoadBits r)
 
 static inline RoadBits DiagDirToRoadBits(DiagDirection d)
 {
-	return 1 << (3 ^ d);
+	return 1U << (3 ^ d);
 }
 
 #endif