diff --git a/bridge.h b/bridge.h
--- a/bridge.h
+++ b/bridge.h
@@ -22,4 +22,6 @@ typedef struct Bridge {
 extern const Bridge orig_bridge[MAX_BRIDGES];
 extern Bridge _bridge[MAX_BRIDGES];
 
+uint GetBridgeFoundation(uint tileh, Axis axis);
+
 #endif /* BRIDGE_H */