diff --git a/OpenRa.Game/GameRules/Rules.cs b/OpenRa.Game/GameRules/Rules.cs
index cc98ade92f..a138cca4c3 100755
--- a/OpenRa.Game/GameRules/Rules.cs
+++ b/OpenRa.Game/GameRules/Rules.cs
@@ -10,7 +10,8 @@ namespace OpenRa.Game
 	static class Rules
 	{
 		public static IniFile AllRules;
-		public static Dictionary<string, List<String>> Categories;
+		public static Dictionary<string, List<string>> Categories = new Dictionary<string,List<string>>();
+		public static Dictionary<string, string> UnitCategory;
 		public static InfoLoader<UnitInfo> UnitInfo;
 		public static InfoLoader<WeaponInfo> WeaponInfo;
 		public static InfoLoader<WarheadInfo> WarheadInfo;
@@ -24,39 +25,39 @@ namespace OpenRa.Game
 				FileSystem.Open( "units.ini" ),
 				FileSystem.Open( "campaignUnits.ini" ) );
 
-			Categories = LoadCategories(
-				"BuildingTypes",
-				"InfantryTypes",
-				"VehicleTypes",
-				"ShipTypes",
-				"PlaneTypes",
-				"WeaponTypes",
-				"WarheadTypes",
-				"ProjectileTypes" );
+			LoadCategories(
+				"Building",
+				"Infantry",
+				"Vehicle",
+				"Ship",
+				"Plane" );
+			UnitCategory = Categories.SelectMany( x => x.Value.Select( y => new KeyValuePair<string, string>( y, x.Key ) ) ).ToDictionary( x => x.Key, x => x.Value );
 
 			UnitInfo = new InfoLoader<UnitInfo>(
-				Pair.New<string,Func<string,UnitInfo>>( "BuildingTypes", s => new UnitInfo.BuildingInfo(s)),
-				Pair.New<string,Func<string,UnitInfo>>( "InfantryTypes", s => new UnitInfo.InfantryInfo(s)),
-				Pair.New<string,Func<string,UnitInfo>>( "VehicleTypes", s => new UnitInfo.VehicleInfo(s)),
-				Pair.New<string,Func<string,UnitInfo>>( "ShipTypes", s => new UnitInfo.VehicleInfo(s)),
-				Pair.New<string,Func<string,UnitInfo>>( "PlaneTypes", s => new UnitInfo.VehicleInfo(s)));
+				Pair.New<string,Func<string,UnitInfo>>( "Building", s => new UnitInfo.BuildingInfo(s)),
+				Pair.New<string,Func<string,UnitInfo>>( "Infantry", s => new UnitInfo.InfantryInfo(s)),
+				Pair.New<string,Func<string,UnitInfo>>( "Vehicle", s => new UnitInfo.VehicleInfo(s)),
+				Pair.New<string,Func<string,UnitInfo>>( "Ship", s => new UnitInfo.VehicleInfo(s)),
+				Pair.New<string,Func<string,UnitInfo>>( "Plane", s => new UnitInfo.VehicleInfo(s)));
+
+			LoadCategories(
+				"Weapon",
+				"Warhead",
+				"Projectile" );
 
 			WeaponInfo = new InfoLoader<WeaponInfo>(
-				Pair.New<string,Func<string,WeaponInfo>>("WeaponTypes", _ => new WeaponInfo()));
+				Pair.New<string,Func<string,WeaponInfo>>("Weapon", _ => new WeaponInfo()));
 			WarheadInfo = new InfoLoader<WarheadInfo>(
-				Pair.New<string,Func<string,WarheadInfo>>("WarheadTypes", _ => new WarheadInfo()));
+				Pair.New<string,Func<string,WarheadInfo>>("Warhead", _ => new WarheadInfo()));
 
 			ProjectileInfo = new InfoLoader<ProjectileInfo>(
-				Pair.New<string, Func<string, ProjectileInfo>>("ProjectileTypes", _ => new ProjectileInfo()));
+				Pair.New<string, Func<string, ProjectileInfo>>("Projectile", _ => new ProjectileInfo()));
 		}
 
-		static Dictionary<string, List<string>> LoadCategories( params string[] types )
+		static void LoadCategories( params string[] types )
 		{
-			var ret = new Dictionary<string, List<string>>();
 			foreach( var t in types )
-				ret[ t ] = AllRules.GetSection( t ).Select( x => x.Key.ToLowerInvariant() ).ToList();
-
-			return ret;
+				Categories[ t ] = AllRules.GetSection( t + "Types" ).Select( x => x.Key.ToLowerInvariant() ).ToList();
 		}
 	}
 }
diff --git a/OpenRa.Game/Sidebar.cs b/OpenRa.Game/Sidebar.cs
index 881d2df6b8..fc8b6708b8 100644
--- a/OpenRa.Game/Sidebar.cs
+++ b/OpenRa.Game/Sidebar.cs
@@ -27,7 +27,6 @@ namespace OpenRa.Game
 
 		static string[] groups = new string[] { "Building", "Vehicle", "Ship", "Infantry", "Plane" };
 
-		Dictionary<string, string> itemGroups = new Dictionary<string,string>();				//item->group
 		Dictionary<string, Animation> clockAnimations = new Dictionary<string,Animation>();		//group->clockAnimation
 		
 		List<SidebarItem> items = new List<SidebarItem>();
@@ -78,13 +77,12 @@ namespace OpenRa.Game
 
 		void LoadSprites( string group )
 		{
-			foreach( var u in Rules.Categories[ group + "Types" ] )
+			foreach( var u in Rules.Categories[ group ] )
 			{
 				var unit = Rules.UnitInfo[ u ];
 
 				if( unit.TechLevel != -1 )
 					sprites.Add( unit.Name, SpriteSheetBuilder.LoadSprite( unit.Name + "icon", ".shp" ) );
-				itemGroups.Add( unit.Name, group );
 			}
 		}
 
@@ -129,7 +127,7 @@ namespace OpenRa.Game
 		{
 			foreach( SidebarItem i in items )
 			{
-				var group = itemGroups[ i.techTreeItem.tag ];
+				var group = Rules.UnitCategory[ i.techTreeItem.tag ];
 				var producing = player.Producing( group );
 				if( producing != null && producing.Item == i.techTreeItem.tag )
 				{
@@ -163,7 +161,7 @@ namespace OpenRa.Game
 				var item = GetItem(point);
 				if (item != null)
 				{
-					string group = itemGroups[item.techTreeItem.tag];
+					string group = Rules.UnitCategory[ item.techTreeItem.tag ];
 					if (player.Producing(group) == null)
 					{
 						player.BeginProduction( group, new ProductionItem( item.techTreeItem.tag, 25, 0 ) );
@@ -177,7 +175,7 @@ namespace OpenRa.Game
 				var item = GetItem(point);
 				if( item != null )
 				{
-					string group = itemGroups[ item.techTreeItem.tag ];
+					string group = Rules.UnitCategory[ item.techTreeItem.tag ];
 					player.CancelProduction( group );
 				}
 			}
diff --git a/OpenRa.Game/TechTree/Item.cs b/OpenRa.Game/TechTree/Item.cs
index d7443157a8..d95f447ab4 100755
--- a/OpenRa.Game/TechTree/Item.cs
+++ b/OpenRa.Game/TechTree/Item.cs
@@ -50,7 +50,7 @@ namespace OpenRa.TechTree
 			if (soviet.Remove("tent")) soviet.Add("barr");
 			if (allied.Remove("barr")) allied.Add("tent");
 
-			if( Rules.Categories[ "InfantryTypes" ].Contains( tag ) )
+			if( Rules.UnitCategory[ tag ] == "Infantry" )
 			{
 				if( !allied.Contains( "tent" ) ) allied.Add( "tent" );
 				if( !soviet.Contains( "barr" ) ) soviet.Add( "barr" );
diff --git a/OpenRa.Game/TechTree/TechTree.cs b/OpenRa.Game/TechTree/TechTree.cs
index 0d424e9de9..4682c58f42 100644
--- a/OpenRa.Game/TechTree/TechTree.cs
+++ b/OpenRa.Game/TechTree/TechTree.cs
@@ -34,10 +34,8 @@ namespace OpenRa.TechTree
 
 		void LoadRules()
 		{
-			var allBuildings = Rules.Categories["BuildingTypes"];
-
 			foreach( var unit in Rules.UnitInfo )
-				objects.Add( unit.Key, new Item( unit.Key, unit.Value, allBuildings.Contains( unit.Key ) ) );
+				objects.Add( unit.Key, new Item( unit.Key, unit.Value, Rules.UnitCategory[ unit.Key ] == "Building" ) );
 		}
 
 		public bool Build(string key, bool force)