diff --git a/OpenRA.Mods.RA/Console/ChatCommands.cs b/OpenRA.Mods.RA/Console/ChatCommands.cs
index c103a92a48..6f6bf6bd16 100644
--- a/OpenRA.Mods.RA/Console/ChatCommands.cs
+++ b/OpenRA.Mods.RA/Console/ChatCommands.cs
@@ -29,11 +29,11 @@ namespace OpenRA.Mods.RA
 		{
 			if (message.StartsWith("/"))
 			{
-				var name = message.Substring(1).Split(' ')[0].ToLower();
+				var name = message.Substring(1).Split(' ')[0].ToLowerInvariant();
 				var command = Commands.FirstOrDefault(x => x.Key == name);
 
 				if (command.Value != null)
-					command.Value.InvokeCommand(name.ToLower(), message.Substring(1 + name.Length));
+					command.Value.InvokeCommand(name.ToLowerInvariant(), message.Substring(1 + name.Length));
 				else
 					Game.Debug("{0} is not a valid command.", name);
 
@@ -45,7 +45,7 @@ namespace OpenRA.Mods.RA
 
 		public void RegisterCommand(string name, IChatCommand command)
 		{
-			Commands.Add(name.ToLower(), command);
+			Commands.Add(name.ToLowerInvariant(), command);
 		}
 	}
 
diff --git a/OpenRA.Mods.RA/Lint/CheckSequences.cs b/OpenRA.Mods.RA/Lint/CheckSequences.cs
index 1597d62634..e154d425bd 100644
--- a/OpenRA.Mods.RA/Lint/CheckSequences.cs
+++ b/OpenRA.Mods.RA/Lint/CheckSequences.cs
@@ -27,7 +27,7 @@ namespace OpenRA.Mods.RA
 				foreach (var renderInfo in actorInfo.Value.Traits.WithInterface<RenderSimpleInfo>())
 				{
 					var image = renderInfo.Image ?? actorInfo.Value.Name;
-					if (!sequences.Any(s => s.Key == image.ToLower()) && !actorInfo.Value.Name.Contains("^"))
+					if (!sequences.Any(s => s.Key == image.ToLowerInvariant()) && !actorInfo.Value.Name.Contains("^"))
 						emitWarning("Sprite image {0} from actor {1} has no sequence definition.".F(image, actorInfo.Value.Name));
 				}
 		}
diff --git a/OpenRA.Mods.RA/Minelayer.cs b/OpenRA.Mods.RA/Minelayer.cs
index 9ced402a6f..6f7b4bf1ee 100644
--- a/OpenRA.Mods.RA/Minelayer.cs
+++ b/OpenRA.Mods.RA/Minelayer.cs
@@ -39,7 +39,7 @@ namespace OpenRA.Mods.RA
 		{
 			this.self = self;
 
-			var tileset = self.World.TileSet.Id.ToLower();
+			var tileset = self.World.TileSet.Id.ToLowerInvariant();
 			tile = self.World.Map.SequenceProvider.GetSequence("overlay", "build-valid-{0}".F(tileset)).GetSprite(0);
 		}
 
@@ -119,7 +119,7 @@ namespace OpenRA.Mods.RA
 				minelayer = self;
 				minefieldStart = xy;
 
-				var tileset = self.World.TileSet.Id.ToLower();
+				var tileset = self.World.TileSet.Id.ToLowerInvariant();
 				tileOk = self.World.Map.SequenceProvider.GetSequence("overlay", "build-valid-{0}".F(tileset)).GetSprite(0);
 				tileBlocked = self.World.Map.SequenceProvider.GetSequence("overlay", "build-invalid").GetSprite(0);
 			}
diff --git a/OpenRA.Mods.RA/Orders/PlaceBuildingOrderGenerator.cs b/OpenRA.Mods.RA/Orders/PlaceBuildingOrderGenerator.cs
index 5fd40ee8f9..53dd148698 100644
--- a/OpenRA.Mods.RA/Orders/PlaceBuildingOrderGenerator.cs
+++ b/OpenRA.Mods.RA/Orders/PlaceBuildingOrderGenerator.cs
@@ -30,7 +30,7 @@ namespace OpenRA.Mods.RA.Orders
 		{
 			Producer = producer;
 			Building = name;
-			var tileset = producer.World.TileSet.Id.ToLower();
+			var tileset = producer.World.TileSet.Id.ToLowerInvariant();
 			BuildingInfo = producer.World.Map.Rules.Actors[Building].Traits.Get<BuildingInfo>();
 
 			buildOk = producer.World.Map.SequenceProvider.GetSequence("overlay", "build-valid-{0}".F(tileset)).GetSprite(0);
diff --git a/OpenRA.Mods.RA/SupportPowers/ChronoshiftPower.cs b/OpenRA.Mods.RA/SupportPowers/ChronoshiftPower.cs
index ac0f304c0d..f672495fe4 100644
--- a/OpenRA.Mods.RA/SupportPowers/ChronoshiftPower.cs
+++ b/OpenRA.Mods.RA/SupportPowers/ChronoshiftPower.cs
@@ -181,7 +181,7 @@ namespace OpenRA.Mods.RA
 				this.sourceLocation = sourceLocation;
 				this.range = ((ChronoshiftPowerInfo)power.Info).Range;
 
-				var tileset = manager.self.World.TileSet.Id.ToLower();
+				var tileset = manager.self.World.TileSet.Id.ToLowerInvariant();
 				validTile = world.Map.SequenceProvider.GetSequence("overlay", "target-valid-{0}".F(tileset)).GetSprite(0);
 				invalidTile = world.Map.SequenceProvider.GetSequence("overlay", "target-invalid").GetSprite(0);
 				sourceTile = world.Map.SequenceProvider.GetSequence("overlay", "target-select").GetSprite(0);