diff --git a/OpenRA.Mods.Common/Pathfinder/BasePathSearch.cs b/OpenRA.Mods.Common/Pathfinder/BasePathSearch.cs
index 13c8c0e79d..8fba8f3e09 100644
--- a/OpenRA.Mods.Common/Pathfinder/BasePathSearch.cs
+++ b/OpenRA.Mods.Common/Pathfinder/BasePathSearch.cs
@@ -23,11 +23,6 @@ namespace OpenRA.Mods.Common.Pathfinder
 		/// </summary>
 		IGraph<CellInfo> Graph { get; }
 
-		/// <summary>
-		/// The open queue where nodes that are worth to consider are stored by their estimator
-		/// </summary>
-		IPriorityQueue<CPos> OpenQueue { get; }
-
 		/// <summary>
 		/// Stores the analyzed nodes by the expand function
 		/// </summary>
@@ -62,6 +57,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 		/// <returns>Whether the location is a target</returns>
 		bool IsTarget(CPos location);
 
+		bool CanExpand { get; }
 		CPos Expand();
 	}
 
@@ -69,7 +65,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 	{
 		public IGraph<CellInfo> Graph { get; set; }
 
-		public IPriorityQueue<CPos> OpenQueue { get; protected set; }
+		protected IPriorityQueue<CPos> OpenQueue { get; private set; }
 
 		public abstract IEnumerable<Pair<CPos, int>> Considered { get; }
 
@@ -84,7 +80,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 		// points considered and their Heuristics to reach
 		// the target. It pretty match identifies, in conjunction of the Actor,
 		// a deterministic set of calculations
-		protected IPriorityQueue<CPos> startPoints;
+		protected readonly IPriorityQueue<CPos> startPoints;
 
 		protected BasePathSearch(IGraph<CellInfo> graph)
 		{
@@ -165,6 +161,7 @@ namespace OpenRA.Mods.Common.Pathfinder
 			return isGoal(location);
 		}
 
+		public bool CanExpand { get { return !OpenQueue.Empty; } }
 		public abstract CPos Expand();
 	}
 }
diff --git a/OpenRA.Mods.Common/Traits/World/PathFinder.cs b/OpenRA.Mods.Common/Traits/World/PathFinder.cs
index 6524d67775..405f2b2a28 100644
--- a/OpenRA.Mods.Common/Traits/World/PathFinder.cs
+++ b/OpenRA.Mods.Common/Traits/World/PathFinder.cs
@@ -121,7 +121,7 @@ namespace OpenRA.Mods.Common.Traits
 
 			List<CPos> path = null;
 
-			while (!search.OpenQueue.Empty)
+			while (search.CanExpand)
 			{
 				var p = search.Expand();
 				if (search.IsTarget(p))
@@ -156,7 +156,7 @@ namespace OpenRA.Mods.Common.Traits
 				fromDest.Debug = true;
 			}
 
-			while (!fromSrc.OpenQueue.Empty && !fromDest.OpenQueue.Empty)
+			while (fromSrc.CanExpand && fromDest.CanExpand)
 			{
 				// make some progress on the first search
 				var p = fromSrc.Expand();