diff --git a/.editorconfig b/.editorconfig
index c9cc464d93..7294066eec 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -150,6 +150,9 @@ dotnet_diagnostic.IDE1006.severity = warning
 # Avoid unnecessary zero-length array allocations.
 dotnet_diagnostic.CA1825.severity = warning
 
+# Use string.Contains(char) instead of string.Contains(string) with single characters.
+dotnet_diagnostic.CA1847.severity = warning
+
 ; 4-column tab indentation
 [*.yaml]
 indent_style = tab
diff --git a/OpenRA.Game/FileSystem/FileSystem.cs b/OpenRA.Game/FileSystem/FileSystem.cs
index 3d17b9cc98..e10a48d43d 100644
--- a/OpenRA.Game/FileSystem/FileSystem.cs
+++ b/OpenRA.Game/FileSystem/FileSystem.cs
@@ -63,7 +63,7 @@ namespace OpenRA.FileSystem
 		{
 			// Raw directories are the easiest and one of the most common cases, so try these first
 			var resolvedPath = Platform.ResolvePath(filename);
-			if (!resolvedPath.Contains("|") && Directory.Exists(resolvedPath))
+			if (!resolvedPath.Contains('|') && Directory.Exists(resolvedPath))
 				return new Folder(resolvedPath);
 
 			// Children of another package require special handling
diff --git a/OpenRA.Game/Map/Map.cs b/OpenRA.Game/Map/Map.cs
index 6a61deec2e..201f7fb49a 100644
--- a/OpenRA.Game/Map/Map.cs
+++ b/OpenRA.Game/Map/Map.cs
@@ -1324,7 +1324,7 @@ namespace OpenRA
 		public Stream Open(string filename)
 		{
 			// Explicit package paths never refer to a map
-			if (!filename.Contains("|") && Package.Contains(filename))
+			if (!filename.Contains('|') && Package.Contains(filename))
 				return Package.GetStream(filename);
 
 			return modData.DefaultFileSystem.Open(filename);
@@ -1339,7 +1339,7 @@ namespace OpenRA
 		public bool TryOpen(string filename, out Stream s)
 		{
 			// Explicit package paths never refer to a map
-			if (!filename.Contains("|"))
+			if (!filename.Contains('|'))
 			{
 				s = Package.GetStream(filename);
 				if (s != null)
@@ -1352,7 +1352,7 @@ namespace OpenRA
 		public bool Exists(string filename)
 		{
 			// Explicit package paths never refer to a map
-			if (!filename.Contains("|") && Package.Contains(filename))
+			if (!filename.Contains('|') && Package.Contains(filename))
 				return true;
 
 			return modData.DefaultFileSystem.Exists(filename);
@@ -1361,7 +1361,7 @@ namespace OpenRA
 		public bool IsExternalModFile(string filename)
 		{
 			// Explicit package paths never refer to a map
-			if (filename.Contains("|"))
+			if (filename.Contains('|'))
 				return modData.DefaultFileSystem.IsExternalModFile(filename);
 
 			return false;
diff --git a/OpenRA.Game/Map/MapPreview.cs b/OpenRA.Game/Map/MapPreview.cs
index 4ef4698b3e..cadc31630f 100644
--- a/OpenRA.Game/Map/MapPreview.cs
+++ b/OpenRA.Game/Map/MapPreview.cs
@@ -559,7 +559,7 @@ namespace OpenRA
 		Stream IReadOnlyFileSystem.Open(string filename)
 		{
 			// Explicit package paths never refer to a map
-			if (!filename.Contains("|") && Package.Contains(filename))
+			if (!filename.Contains('|') && Package.Contains(filename))
 				return Package.GetStream(filename);
 
 			return modData.DefaultFileSystem.Open(filename);
@@ -574,7 +574,7 @@ namespace OpenRA
 		bool IReadOnlyFileSystem.TryOpen(string filename, out Stream s)
 		{
 			// Explicit package paths never refer to a map
-			if (!filename.Contains("|"))
+			if (!filename.Contains('|'))
 			{
 				s = Package.GetStream(filename);
 				if (s != null)
@@ -587,7 +587,7 @@ namespace OpenRA
 		bool IReadOnlyFileSystem.Exists(string filename)
 		{
 			// Explicit package paths never refer to a map
-			if (!filename.Contains("|") && Package.Contains(filename))
+			if (!filename.Contains('|') && Package.Contains(filename))
 				return true;
 
 			return modData.DefaultFileSystem.Exists(filename);
@@ -596,7 +596,7 @@ namespace OpenRA
 		bool IReadOnlyFileSystem.IsExternalModFile(string filename)
 		{
 			// Explicit package paths never refer to a map
-			if (filename.Contains("|"))
+			if (filename.Contains('|'))
 				return modData.DefaultFileSystem.IsExternalModFile(filename);
 
 			return false;
diff --git a/OpenRA.Game/Widgets/WidgetLoader.cs b/OpenRA.Game/Widgets/WidgetLoader.cs
index 563c4ad0f0..8058935e94 100644
--- a/OpenRA.Game/Widgets/WidgetLoader.cs
+++ b/OpenRA.Game/Widgets/WidgetLoader.cs
@@ -52,7 +52,7 @@ namespace OpenRA
 
 			parent?.AddChild(widget);
 
-			if (node.Key.Contains("@"))
+			if (node.Key.Contains('@'))
 				FieldLoader.LoadField(widget, "Id", node.Key.Split('@')[1]);
 
 			foreach (var child in node.Value.Nodes)
diff --git a/OpenRA.Mods.Common/UpdateRules/UpdateUtils.cs b/OpenRA.Mods.Common/UpdateRules/UpdateUtils.cs
index cb192b523c..4c8ccfb4d9 100644
--- a/OpenRA.Mods.Common/UpdateRules/UpdateUtils.cs
+++ b/OpenRA.Mods.Common/UpdateRules/UpdateUtils.cs
@@ -47,7 +47,7 @@ namespace OpenRA.Mods.Common.UpdateRules
 		static YamlFileSet LoadExternalMapYaml(ModData modData, MiniYaml yaml, HashSet<string> externalFilenames)
 		{
 			return FieldLoader.GetValue<string[]>("value", yaml.Value)
-				.Where(f => f.Contains("|"))
+				.Where(f => f.Contains('|'))
 				.SelectMany(f => LoadModYaml(modData, FilterExternalModFiles(modData, new[] { f }, externalFilenames)))
 				.ToList();
 		}
@@ -67,7 +67,7 @@ namespace OpenRA.Mods.Common.UpdateRules
 			foreach (var filename in files)
 			{
 				// Ignore any files that aren't in the map bundle
-				if (!filename.Contains("|") && mapPackage.Contains(filename))
+				if (!filename.Contains('|') && mapPackage.Contains(filename))
 					fileSet.Add((mapPackage, filename, MiniYaml.FromStream(mapPackage.GetStream(filename), filename, false)));
 				else if (modData.ModFiles.Exists(filename))
 					externalFilenames.Add(filename);
@@ -145,7 +145,7 @@ namespace OpenRA.Mods.Common.UpdateRules
 		{
 			foreach (var f in files)
 			{
-				if (f.Contains("|") && modData.DefaultFileSystem.IsExternalModFile(f))
+				if (f.Contains('|') && modData.DefaultFileSystem.IsExternalModFile(f))
 				{
 					externalFilenames.Add(f);
 					continue;
diff --git a/OpenRA.Mods.Common/UtilityCommands/CheckExplicitInterfacesCommand.cs b/OpenRA.Mods.Common/UtilityCommands/CheckExplicitInterfacesCommand.cs
index 3caa765bbd..1618f21b26 100644
--- a/OpenRA.Mods.Common/UtilityCommands/CheckExplicitInterfacesCommand.cs
+++ b/OpenRA.Mods.Common/UtilityCommands/CheckExplicitInterfacesCommand.cs
@@ -111,7 +111,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 
 		static bool IsExplicitInterfaceProperty(PropertyInfo pi)
 		{
-			return pi.Name.Contains(".");
+			return pi.Name.Contains('.');
 		}
 
 		void OnViolation(Type implementor, Type interfaceType, MemberInfo violator)