diff --git a/OpenRA.Game/GameRules/RulesetCache.cs b/OpenRA.Game/GameRules/RulesetCache.cs
index c119e1c6c4..5c5d37d113 100755
--- a/OpenRA.Game/GameRules/RulesetCache.cs
+++ b/OpenRA.Game/GameRules/RulesetCache.cs
@@ -31,13 +31,16 @@ namespace OpenRA
 		readonly Dictionary<string, TileSet> tileSetCache = new Dictionary<string, TileSet>();
 		readonly Dictionary<string, SequenceCache> sequenceCaches = new Dictionary<string, SequenceCache>();
 
-		public Action OnProgress;
+		public event EventHandler LoadingProgress;
+		void RaiseProgress()
+		{
+			if (LoadingProgress != null)
+				LoadingProgress(this, new EventArgs());
+		}
 
 		public RulesetCache(ModData modData)
 		{
 			this.modData = modData;
-
-			OnProgress = () => { if (modData.LoadScreen != null) modData.LoadScreen.Display(); };
 		}
 
 		public Ruleset LoadDefaultRules()
@@ -57,31 +60,23 @@ namespace OpenRA
 			Dictionary<string, string> movies;
 			Dictionary<string, TileSet> tileSets;
 
-			OnProgress();
 			using (new PerfTimer("Actors"))
 				actors = LoadYamlRules(actorCache, m.Rules, map.RuleDefinitions, (k, y) => new ActorInfo(k.Key.ToLowerInvariant(), k.Value, y));
-			OnProgress();
 			using (new PerfTimer("Weapons"))
 				weapons = LoadYamlRules(weaponCache, m.Weapons, map.WeaponDefinitions, (k, _) => new WeaponInfo(k.Key.ToLowerInvariant(), k.Value));
-			OnProgress();
 			using (new PerfTimer("Voices"))
 				voices = LoadYamlRules(voiceCache, m.Voices, map.VoiceDefinitions, (k, _) => new SoundInfo(k.Value));
-			OnProgress();
 			using (new PerfTimer("Notifications"))
 				notifications = LoadYamlRules(notificationCache, m.Notifications, map.NotificationDefinitions, (k, _) => new SoundInfo(k.Value));
-			OnProgress();
 			using (new PerfTimer("Music"))
 				music = LoadYamlRules(musicCache, m.Music, new List<MiniYamlNode>(), (k, _) => new MusicInfo(k.Key, k.Value));
-			OnProgress();
 			using (new PerfTimer("Movies"))
 				movies = LoadYamlRules(movieCache, m.Movies, new List<MiniYamlNode>(), (k, v) => k.Value.Value);
-			OnProgress();
 			using (new PerfTimer("TileSets"))
 				tileSets = LoadTileSets(tileSetCache, sequenceCaches, m.TileSets);
 
 			var sequences = sequenceCaches.ToDictionary(kvp => kvp.Key, kvp => new SequenceProvider(kvp.Value, map));
 
-			OnProgress();
 			return new Ruleset(actors, weapons, voices, notifications, music, movies, tileSets, sequences);
 		}
 
@@ -90,6 +85,8 @@ namespace OpenRA
 			string[] files, List<MiniYamlNode> nodes,
 			Func<MiniYamlNode, Dictionary<string, MiniYaml>, T> f)
 		{
+			RaiseProgress();
+
 			var inputKey = string.Concat(string.Join("|", files), "|", nodes.WriteToString());
 
 			var mergedNodes = files
@@ -105,12 +102,15 @@ namespace OpenRA
 
 				t = f(wkv, wyy);
 				itemCache.Add(key, t);
+
+				RaiseProgress();
 				return t;
 			};
 
 			var yy = mergedNodes.ToDictionary(x => x.Key, x => x.Value);
 			var itemSet = mergedNodes.ToDictionaryWithConflictLog(kv => kv.Key.ToLowerInvariant(), kv => wrap(kv, yy), "LoadYamlRules", null, null);
 
+			RaiseProgress();
 			return itemSet;
 		}
 
diff --git a/OpenRA.Game/Graphics/CursorProvider.cs b/OpenRA.Game/Graphics/CursorProvider.cs
index f5313905df..9c00994f49 100644
--- a/OpenRA.Game/Graphics/CursorProvider.cs
+++ b/OpenRA.Game/Graphics/CursorProvider.cs
@@ -22,12 +22,8 @@ namespace OpenRA.Graphics
 		Dictionary<string, CursorSequence> cursors;
 		Cache<string, PaletteReference> palettes;
 
-		public Action OnProgress;
-
 		public CursorProvider(ModData modData)
 		{
-			OnProgress = () => { if (modData.LoadScreen != null) modData.LoadScreen.Display(); };
-
 			var sequenceFiles = modData.Manifest.Cursors;
 
 			cursors = new Dictionary<string, CursorSequence>();
@@ -65,8 +61,6 @@ namespace OpenRA.Graphics
 
 		void LoadSequencesForCursor(SpriteLoader loader, string cursorSrc, MiniYaml cursor)
 		{
-			OnProgress();
-
 			foreach (var sequence in cursor.Nodes)
 				cursors.Add(sequence.Key, new CursorSequence(loader, cursorSrc, cursor.Value, sequence.Value));
 		}
diff --git a/OpenRA.Game/Graphics/SequenceProvider.cs b/OpenRA.Game/Graphics/SequenceProvider.cs
index f250216dbf..73ee8ef1ac 100644
--- a/OpenRA.Game/Graphics/SequenceProvider.cs
+++ b/OpenRA.Game/Graphics/SequenceProvider.cs
@@ -68,12 +68,8 @@ namespace OpenRA.Graphics
 
 		readonly Dictionary<string, Lazy<IReadOnlyDictionary<string, Sequence>>> sequenceCache = new Dictionary<string, Lazy<IReadOnlyDictionary<string, Sequence>>>();
 
-		public Action OnProgress;
-
 		public SequenceCache(ModData modData, TileSet tileSet)
 		{
-			OnProgress = () => { if (modData.LoadScreen != null) modData.LoadScreen.Display(); };
-
 			this.modData = modData;
 
 			spriteLoader = Exts.Lazy(() => new SpriteLoader(tileSet.Extensions, new SheetBuilder(SheetType.Indexed)));
@@ -87,8 +83,6 @@ namespace OpenRA.Graphics
 
 		IReadOnlyDictionary<string, Lazy<IReadOnlyDictionary<string, Sequence>>> Load(List<MiniYamlNode> sequenceNodes)
 		{
-			OnProgress();
-
 			var sequenceFiles = modData.Manifest.Sequences;
 
 			var nodes = sequenceFiles
@@ -113,8 +107,6 @@ namespace OpenRA.Graphics
 					sequenceCache.Add(key, t);
 					items.Add(node.Key, t);
 				}
-
-				OnProgress();
 			}
 
 			return new ReadOnlyDictionary<string, Lazy<IReadOnlyDictionary<string, Sequence>>>(items);
diff --git a/OpenRA.Game/ModData.cs b/OpenRA.Game/ModData.cs
index cb9ba5cf91..4ad17eaaf7 100644
--- a/OpenRA.Game/ModData.cs
+++ b/OpenRA.Game/ModData.cs
@@ -42,6 +42,7 @@ namespace OpenRA
 			LoadScreen.Display();
 			WidgetLoader = new WidgetLoader(this);
 			RulesetCache = new RulesetCache(this);
+			RulesetCache.LoadingProgress += HandleLoadingProgress;
 			MapCache = new MapCache(this);
 
 			// HACK: Mount only local folders so we have a half-working environment for the asset installer
@@ -50,6 +51,16 @@ namespace OpenRA
 				GlobalFileSystem.Mount(dir);
 
 			defaultRules = Exts.Lazy(() => RulesetCache.LoadDefaultRules());
+
+			initialThreadId = System.Threading.Thread.CurrentThread.ManagedThreadId;
+		}
+
+		// HACK: Only update the loading screen if we're in the main thread.
+		int initialThreadId;
+		void HandleLoadingProgress(object sender, EventArgs e)
+		{
+			if (LoadScreen != null && System.Threading.Thread.CurrentThread.ManagedThreadId == initialThreadId)
+				LoadScreen.Display();
 		}
 
 		public void InitializeLoaders()