--- a/src/industry.h	Thu Aug 30 19:20:15 2007 +0000
+++ b/src/industry.h	Thu Aug 30 20:40:33 2007 +0000
@@ -123,7 +123,7 @@
 	Industry(TileIndex tile = 0) : xy(tile) {}
 	~Industry();
 
-	bool IsValid() const { return this->xy != 0; }
+	inline bool IsValid() const { return this->xy != 0; }
 };
 
 struct IndustryTileTable {