diff --git a/.editorconfig b/.editorconfig
index 07f87bfa59..d337be3a2f 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -144,6 +144,9 @@ dotnet_diagnostic.IDE0017.severity = warning
 # Inline variable declaration.
 dotnet_diagnostic.IDE0018.severity = warning
 
+# Use pattern matching to avoid 'as' followed by a 'null' check.
+dotnet_diagnostic.IDE0019.severity = warning
+
 # Collection initialization can be simplified
 dotnet_diagnostic.IDE0028.severity = warning
 
diff --git a/OpenRA.Mods.Cnc/Traits/Minelayer.cs b/OpenRA.Mods.Cnc/Traits/Minelayer.cs
index a24e57bcfa..6848ba1c3f 100644
--- a/OpenRA.Mods.Cnc/Traits/Minelayer.cs
+++ b/OpenRA.Mods.Cnc/Traits/Minelayer.cs
@@ -146,11 +146,10 @@ namespace OpenRA.Mods.Cnc.Traits
 				minefieldStart = order.ExtraLocation;
 
 				var movement = self.Trait<IPositionable>();
-				var mobile = movement as Mobile;
 
 				var minefield = GetMinefieldCells(minefieldStart, cell, Info.MinefieldDepth)
 					.Where(c => IsCellAcceptable(self, c) && self.Owner.Shroud.IsExplored(c)
-						&& movement.CanEnterCell(c, null, BlockedByActor.Immovable) && (mobile != null && mobile.CanStayInCell(c)))
+						&& movement.CanEnterCell(c, null, BlockedByActor.Immovable) && (movement is Mobile mobile && mobile.CanStayInCell(c)))
 					.OrderBy(c => (c - minefieldStart).LengthSquared).ToList();
 
 				self.QueueActivity(order.Queued, new LayMines(self, minefield));
diff --git a/OpenRA.Mods.Common/Installer/SourceResolvers/GogSourceResolver.cs b/OpenRA.Mods.Common/Installer/SourceResolvers/GogSourceResolver.cs
index f5179a3bb1..4f4f3dd74b 100644
--- a/OpenRA.Mods.Common/Installer/SourceResolvers/GogSourceResolver.cs
+++ b/OpenRA.Mods.Common/Installer/SourceResolvers/GogSourceResolver.cs
@@ -34,12 +34,8 @@ namespace OpenRA.Mods.Common.Installer
 			var prefixes = new[] { "HKEY_LOCAL_MACHINE\\Software\\", "HKEY_LOCAL_MACHINE\\SOFTWARE\\Wow6432Node\\" };
 
 			foreach (var prefix in prefixes)
-			{
-				var installDir = Registry.GetValue($"{prefix}GOG.com\\Games\\{appId.Value}", "path", null) as string;
-
-				if (installDir != null)
+				if (Registry.GetValue($"{prefix}GOG.com\\Games\\{appId.Value}", "path", null) is string installDir)
 					return installDir;
-			}
 
 			return null;
 		}
diff --git a/OpenRA.Mods.Common/Pathfinder/HierarchicalPathFinder.cs b/OpenRA.Mods.Common/Pathfinder/HierarchicalPathFinder.cs
index a74eb201a3..5f3e909d1d 100644
--- a/OpenRA.Mods.Common/Pathfinder/HierarchicalPathFinder.cs
+++ b/OpenRA.Mods.Common/Pathfinder/HierarchicalPathFinder.cs
@@ -646,8 +646,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 		/// </summary>
 		bool ActorIsBlocking(Actor actor)
 		{
-			var mobile = actor.OccupiesSpace as Mobile;
-			var isMovable = mobile != null && !mobile.IsTraitDisabled && !mobile.IsTraitPaused && !mobile.IsImmovable;
+			var isMovable = actor.OccupiesSpace is Mobile mobile && !mobile.IsTraitDisabled && !mobile.IsTraitPaused && !mobile.IsImmovable;
 			if (isMovable)
 				return false;