diff --git a/OpenRA.Game/Map/MapPreview.cs b/OpenRA.Game/Map/MapPreview.cs
index 5f07081c9d..ab2fbeb5f6 100644
--- a/OpenRA.Game/Map/MapPreview.cs
+++ b/OpenRA.Game/Map/MapPreview.cs
@@ -137,8 +137,8 @@ namespace OpenRA
 							sources = sources.Append(RuleDefinitions.Nodes.Where(IsLoadableRuleDefinition).ToList());
 
 						var yamlNodes = MiniYaml.Merge(sources);
-						WorldActorInfo = new ActorInfo(modData.ObjectCreator, "world", yamlNodes.First(n => n.Key.ToLowerInvariant() == "world").Value);
-						PlayerActorInfo = new ActorInfo(modData.ObjectCreator, "player", yamlNodes.First(n => n.Key.ToLowerInvariant() == "player").Value);
+						WorldActorInfo = new ActorInfo(modData.ObjectCreator, "world", yamlNodes.First(n => string.Equals(n.Key, "world", StringComparison.InvariantCultureIgnoreCase)).Value);
+						PlayerActorInfo = new ActorInfo(modData.ObjectCreator, "player", yamlNodes.First(n => string.Equals(n.Key, "player", StringComparison.InvariantCultureIgnoreCase)).Value);
 						return;
 					}
 				}
diff --git a/OpenRA.Mods.Common/Lint/CheckWorldAndPlayerInherits.cs b/OpenRA.Mods.Common/Lint/CheckWorldAndPlayerInherits.cs
index 587afbaddd..de8e1e8de7 100644
--- a/OpenRA.Mods.Common/Lint/CheckWorldAndPlayerInherits.cs
+++ b/OpenRA.Mods.Common/Lint/CheckWorldAndPlayerInherits.cs
@@ -76,7 +76,7 @@ namespace OpenRA.Mods.Common.Lint
 
 		void CheckInheritance(Action<string> emitError, string actor, Dictionary<string, List<string>> inheritsMap)
 		{
-			var toResolve = new Queue<string>(inheritsMap.Keys.Where(k => k.ToLowerInvariant() == actor.ToLowerInvariant()));
+			var toResolve = new Queue<string>(inheritsMap.Keys.Where(k => string.Equals(k, actor, StringComparison.InvariantCultureIgnoreCase)));
 			while (toResolve.TryDequeue(out var key))
 			{
 				// Missing keys are a fatal merge error, so will have already been reported by other lint checks
diff --git a/OpenRA.Mods.Common/Traits/Palettes/PaletteFromFile.cs b/OpenRA.Mods.Common/Traits/Palettes/PaletteFromFile.cs
index 2c17249e45..00f314e32c 100644
--- a/OpenRA.Mods.Common/Traits/Palettes/PaletteFromFile.cs
+++ b/OpenRA.Mods.Common/Traits/Palettes/PaletteFromFile.cs
@@ -66,7 +66,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		public void LoadPalettes(WorldRenderer wr)
 		{
-			if (info.Tileset == null || info.Tileset.ToLowerInvariant() == world.Map.Tileset.ToLowerInvariant())
+			if (info.Tileset == null || string.Equals(info.Tileset, world.Map.Tileset, StringComparison.InvariantCultureIgnoreCase))
 				wr.AddPalette(info.Name, ((IProvidesCursorPaletteInfo)info).ReadPalette(world.Map), info.AllowModifiers);
 		}
 
diff --git a/OpenRA.Mods.Common/Traits/Palettes/PaletteFromPng.cs b/OpenRA.Mods.Common/Traits/Palettes/PaletteFromPng.cs
index 3ed42fb8a8..3beed0b169 100644
--- a/OpenRA.Mods.Common/Traits/Palettes/PaletteFromPng.cs
+++ b/OpenRA.Mods.Common/Traits/Palettes/PaletteFromPng.cs
@@ -74,7 +74,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		public void LoadPalettes(WorldRenderer wr)
 		{
-			if (info.Tileset != null && info.Tileset.ToLowerInvariant() != world.Map.Tileset.ToLowerInvariant())
+			if (info.Tileset != null && !string.Equals(info.Tileset, world.Map.Tileset, StringComparison.InvariantCultureIgnoreCase))
 				return;
 
 			wr.AddPalette(info.Name, ((IProvidesCursorPaletteInfo)info).ReadPalette(world.Map), info.AllowModifiers);
diff --git a/OpenRA.Mods.Common/Traits/Palettes/PaletteFromRGBA.cs b/OpenRA.Mods.Common/Traits/Palettes/PaletteFromRGBA.cs
index 44fe850462..16eeec0372 100644
--- a/OpenRA.Mods.Common/Traits/Palettes/PaletteFromRGBA.cs
+++ b/OpenRA.Mods.Common/Traits/Palettes/PaletteFromRGBA.cs
@@ -61,7 +61,7 @@ namespace OpenRA.Mods.Common.Traits
 		public void LoadPalettes(WorldRenderer wr)
 		{
 			// Enable palette only for a specific tileset
-			if (info.Tileset != null && info.Tileset.ToLowerInvariant() != world.Map.Tileset.ToLowerInvariant())
+			if (info.Tileset != null && !string.Equals(info.Tileset, world.Map.Tileset, System.StringComparison.InvariantCultureIgnoreCase))
 				return;
 
 			var a = info.A / 255f;
diff --git a/OpenRA.Mods.Common/UpdateRules/Rules/20200202/RemoveYesNo.cs b/OpenRA.Mods.Common/UpdateRules/Rules/20200202/RemoveYesNo.cs
index e77758f93a..e0bcbef76b 100644
--- a/OpenRA.Mods.Common/UpdateRules/Rules/20200202/RemoveYesNo.cs
+++ b/OpenRA.Mods.Common/UpdateRules/Rules/20200202/RemoveYesNo.cs
@@ -31,9 +31,9 @@ namespace OpenRA.Mods.Common.UpdateRules.Rules
 					if (value == null)
 						continue;
 
-					if (value.ToLowerInvariant() == "yes")
+					if (string.Equals(value, "yes", System.StringComparison.InvariantCultureIgnoreCase))
 						n.ReplaceValue("true");
-					else if (value.ToLowerInvariant() == "no")
+					else if (string.Equals(value, "no", System.StringComparison.InvariantCultureIgnoreCase))
 						n.ReplaceValue("false");
 				}
 			}
diff --git a/OpenRA.Mods.Common/UtilityCommands/ImportLegacyMapCommand.cs b/OpenRA.Mods.Common/UtilityCommands/ImportLegacyMapCommand.cs
index cfef599035..1323076c56 100644
--- a/OpenRA.Mods.Common/UtilityCommands/ImportLegacyMapCommand.cs
+++ b/OpenRA.Mods.Common/UtilityCommands/ImportLegacyMapCommand.cs
@@ -389,7 +389,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 				try
 				{
 					var parts = s.Value.Split(',');
-					if (parts[0] == "")
+					if (string.IsNullOrEmpty(parts[0]))
 						parts[0] = "Neutral";
 
 					if (!players.Contains(parts[0]))
diff --git a/OpenRA.Mods.D2k/UtilityCommands/D2kMapImporter.cs b/OpenRA.Mods.D2k/UtilityCommands/D2kMapImporter.cs
index 0869b73a7e..ab0019c227 100644
--- a/OpenRA.Mods.D2k/UtilityCommands/D2kMapImporter.cs
+++ b/OpenRA.Mods.D2k/UtilityCommands/D2kMapImporter.cs
@@ -341,7 +341,7 @@ namespace OpenRA.Mods.D2k.UtilityCommands
 			tileSetsFromYaml = terrainInfo.Templates.Where(t =>
 			{
 				var templateInfo = (DefaultTerrainTemplateInfo)t.Value;
-				return templateInfo.Frames != null && templateInfo.Images[0].ToLowerInvariant() == tilesetName.ToLowerInvariant();
+				return templateInfo.Frames != null && string.Equals(templateInfo.Images[0], tilesetName, StringComparison.InvariantCultureIgnoreCase);
 			}).Select(ts => ts.Value).ToList();
 
 			var players = new MapPlayers(map.Rules, playerCount);
@@ -416,7 +416,7 @@ namespace OpenRA.Mods.D2k.UtilityCommands
 		TerrainTile GetTile(int tileIndex)
 		{
 			// Some tiles are duplicates of other tiles, just on a different tileset
-			if (tilesetName.ToLowerInvariant() == "bloxbgbs.r8")
+			if (string.Equals(tilesetName, "bloxbgbs.r8", StringComparison.InvariantCultureIgnoreCase))
 			{
 				if (tileIndex == 355)
 					return new TerrainTile(441, 0);
@@ -425,7 +425,7 @@ namespace OpenRA.Mods.D2k.UtilityCommands
 					return new TerrainTile(442, 0);
 			}
 
-			if (tilesetName.ToLowerInvariant() == "bloxtree.r8")
+			if (string.Equals(tilesetName, "bloxtree.r8", StringComparison.InvariantCultureIgnoreCase))
 			{
 				var indices = new[] { 683, 684, 685, 706, 703, 704, 705, 726, 723, 724, 725, 746, 743, 744, 745, 747 };
 				for (var i = 0; i < 16; i++)
@@ -446,7 +446,7 @@ namespace OpenRA.Mods.D2k.UtilityCommands
 					return new TerrainTile(215, 0);
 			}
 
-			if (tilesetName.ToLowerInvariant() == "bloxwast.r8")
+			if (string.Equals(tilesetName, "bloxwast.r8", StringComparison.InvariantCultureIgnoreCase))
 			{
 				if (tileIndex == 342)
 					return new TerrainTile(250, 0);