diff --git a/OpenRA.Game/Traits/TraitsInterfaces.cs b/OpenRA.Game/Traits/TraitsInterfaces.cs
index 00df96503e..678df47f0d 100755
--- a/OpenRA.Game/Traits/TraitsInterfaces.cs
+++ b/OpenRA.Game/Traits/TraitsInterfaces.cs
@@ -217,7 +217,7 @@ namespace OpenRA.Traits
             Stance oldStance, Stance newStance);
     }
 
-    public interface ILintPass { void Run(Action<string> emitError); }
+    public interface ILintPass { void Run(Action<string> emitError, Action<string> emitWarning); }
 
 	public interface IObjectivesPanel { string ObjectivesPanel { get; } }
 }
diff --git a/OpenRA.Mods.RA/AttackBase.cs b/OpenRA.Mods.RA/AttackBase.cs
index a5dbc91cda..ac913aa0da 100644
--- a/OpenRA.Mods.RA/AttackBase.cs
+++ b/OpenRA.Mods.RA/AttackBase.cs
@@ -48,7 +48,7 @@ namespace OpenRA.Mods.RA
 		}
 	}
 
-	public abstract class AttackBase : IIssueOrder, IResolveOrder, ITick, IExplodeModifier, IOrderVoice, ISync
+	public abstract class AttackBase : IIssueOrder, IResolveOrder, ITick, IExplodeModifier, IOrderVoice
 	{
 		public bool IsAttacking { get; internal set; }
 
diff --git a/OpenRA.Mods.RA/Lint/CheckAutotargetWiring.cs b/OpenRA.Mods.RA/Lint/CheckAutotargetWiring.cs
index f5aa9cff64..49f835668f 100644
--- a/OpenRA.Mods.RA/Lint/CheckAutotargetWiring.cs
+++ b/OpenRA.Mods.RA/Lint/CheckAutotargetWiring.cs
@@ -19,7 +19,7 @@ namespace OpenRA.Mods.RA
 {
 	class CheckAutotargetWiring : ILintPass
 	{
-		public void Run(Action<string> emitError)
+		public void Run(Action<string> emitError, Action<string> emitWarning)
         {
             foreach( var i in Rules.Info )
 			{
diff --git a/OpenRA.Mods.RA/Lint/CheckSyncAnnotations.cs b/OpenRA.Mods.RA/Lint/CheckSyncAnnotations.cs
new file mode 100644
index 0000000000..84feceb60d
--- /dev/null
+++ b/OpenRA.Mods.RA/Lint/CheckSyncAnnotations.cs
@@ -0,0 +1,42 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2011 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made 
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using OpenRA.FileFormats;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA
+{
+	class CheckSyncAnnotations : ILintPass
+	{
+		public void Run(Action<string> emitError, Action<string> emitWarning)
+		{
+			/* first, check all the types implementing ISync */
+			foreach (var t in Game.modData.ObjectCreator.GetTypesImplementing<ISync>())
+				if (!HasAnySyncFields(t))
+					emitWarning("{0} has ISync but nothing marked with [Sync]".F(t.Name));
+		}
+		
+		bool HasAnySyncFields(Type t)
+		{
+			var flags = BindingFlags.Public | BindingFlags.NonPublic
+				| BindingFlags.Instance | BindingFlags.FlattenHierarchy;
+
+			var fs = t.GetFields(flags);
+			var ps = t.GetProperties(flags);
+			return fs.Any(f => f.HasAttribute<SyncAttribute>()) ||
+				ps.Any(p => p.HasAttribute<SyncAttribute>());
+		}
+	}
+}
diff --git a/OpenRA.Mods.RA/Lint/LintBuildablePrerequisites.cs b/OpenRA.Mods.RA/Lint/LintBuildablePrerequisites.cs
index c263fd9523..bd220c3d18 100644
--- a/OpenRA.Mods.RA/Lint/LintBuildablePrerequisites.cs
+++ b/OpenRA.Mods.RA/Lint/LintBuildablePrerequisites.cs
@@ -19,7 +19,7 @@ namespace OpenRA.Mods.RA
 {
     class LintBuildablePrerequisites : ILintPass
     {
-        public void Run(Action<string> emitError)
+        public void Run(Action<string> emitError, Action<string> emitWarning)
         {
 			var providedPrereqs = Rules.Info.Keys.Concat( 
 				Rules.Info.SelectMany( a => a.Value.Traits
diff --git a/OpenRA.Mods.RA/OpenRA.Mods.RA.csproj b/OpenRA.Mods.RA/OpenRA.Mods.RA.csproj
index 3306530481..244f2e109f 100644
--- a/OpenRA.Mods.RA/OpenRA.Mods.RA.csproj
+++ b/OpenRA.Mods.RA/OpenRA.Mods.RA.csproj
@@ -71,6 +71,7 @@
     <Compile Include="GivesBounty.cs" />
     <Compile Include="Lint\LintBuildablePrerequisites.cs" />
     <Compile Include="Lint\CheckAutotargetWiring.cs" />
+    <Compile Include="Lint\CheckSyncAnnotations.cs" />
     <Compile Include="ProductionBar.cs" />
     <Compile Include="Render\RenderEditorOnly.cs" />
     <Compile Include="SmokeTrailWhenDamaged.cs" />
diff --git a/OpenRA.Mods.RA/SupportPowers/GpsPower.cs b/OpenRA.Mods.RA/SupportPowers/GpsPower.cs
index e7cf00b2e4..e8fe5942fb 100755
--- a/OpenRA.Mods.RA/SupportPowers/GpsPower.cs
+++ b/OpenRA.Mods.RA/SupportPowers/GpsPower.cs
@@ -84,7 +84,7 @@ namespace OpenRA.Mods.RA
 		public override object Create(ActorInitializer init) { return new GpsPower(init.self, this); }
 	}
 
-	class GpsPower : SupportPower, INotifyKilled, ISync, INotifyStanceChanged, INotifySold, INotifyCapture
+	class GpsPower : SupportPower, INotifyKilled, INotifyStanceChanged, INotifySold, INotifyCapture
 	{
 		GpsWatcher owner;
 
diff --git a/RALint/RALint.cs b/RALint/RALint.cs
index a396aad1dc..f4a09dd9ac 100644
--- a/RALint/RALint.cs
+++ b/RALint/RALint.cs
@@ -28,6 +28,11 @@ namespace RALint
 			++errors;
 		}
 
+		static void EmitWarning(string e)
+		{
+			Console.WriteLine("RALint(1,1): Warning: {0}", e);
+		}
+
 		static int Main(string[] args)
 		{
 			try
@@ -52,7 +57,7 @@ namespace RALint
 
                     Console.WriteLine("CustomPass: {0}".F(customPassType.ToString()));
 
-                    customPass.Run(EmitError);
+                    customPass.Run(EmitError, EmitWarning);
                 }
 
 				if (errors > 0)