diff --git a/OpenRA.Game/Traits/TraitsInterfaces.cs b/OpenRA.Game/Traits/TraitsInterfaces.cs
index 678df47f0d..b8ab0f7b3d 100755
--- a/OpenRA.Game/Traits/TraitsInterfaces.cs
+++ b/OpenRA.Game/Traits/TraitsInterfaces.cs
@@ -142,7 +142,7 @@ namespace OpenRA.Traits
     public interface ICrushable
     {
         void OnCrush(Actor crusher);
-        IEnumerable<string> CrushClasses { get; }
+		bool CrushableBy(string[] crushClasses, Player owner);
     }
 
     public struct Renderable
diff --git a/OpenRA.Mods.RA/Buildings/Wall.cs b/OpenRA.Mods.RA/Buildings/Wall.cs
index da22175d29..e5e486de0a 100755
--- a/OpenRA.Mods.RA/Buildings/Wall.cs
+++ b/OpenRA.Mods.RA/Buildings/Wall.cs
@@ -9,6 +9,7 @@
 #endregion
 
 using System.Collections.Generic;
+using System.Linq;
 using OpenRA.Traits;
 
 namespace OpenRA.Mods.RA.Buildings
@@ -31,7 +32,14 @@ namespace OpenRA.Mods.RA.Buildings
 			this.info = info;
 		}
 		
-		public IEnumerable<string> CrushClasses { get { return info.CrushClasses; } }
+		public bool CrushableBy(string[] crushClasses, Player crushOwner)
+		{
+			if (crushOwner.Stances[self.Owner] == Stance.Ally)
+				return false;
+
+			return info.CrushClasses.Intersect(crushClasses).Any();
+		}
+
 		public void OnCrush(Actor crusher)
 		{
 			self.Kill(crusher);
diff --git a/OpenRA.Mods.RA/Crate.cs b/OpenRA.Mods.RA/Crate.cs
index 03ede79c5f..7f38113604 100644
--- a/OpenRA.Mods.RA/Crate.cs
+++ b/OpenRA.Mods.RA/Crate.cs
@@ -122,6 +122,9 @@ namespace OpenRA.Mods.RA
 				self.World.ActorMap.Add(self, this);
 		}
 
-		public IEnumerable<string> CrushClasses { get { yield return "crate"; } }
+		public bool CrushableBy(string[] crushClasses, Player owner)
+		{
+			return crushClasses.Contains("crate");
+		}
 	}
 }
diff --git a/OpenRA.Mods.RA/Mine.cs b/OpenRA.Mods.RA/Mine.cs
index ef90aa15b6..1738c1ef35 100644
--- a/OpenRA.Mods.RA/Mine.cs
+++ b/OpenRA.Mods.RA/Mine.cs
@@ -9,6 +9,7 @@
 #endregion
 
 using System.Collections.Generic;
+using System.Linq;
 using OpenRA.Mods.RA.Activities;
 using OpenRA.Traits;
 using OpenRA.FileFormats;
@@ -48,10 +49,13 @@ namespace OpenRA.Mods.RA
 			Combat.DoExplosion(self, info.Weapon, crusher.CenterLocation, 0);
 			self.QueueActivity(new RemoveSelf());
 		}
-		
+
 		// TODO: Re-implement friendly-mine avoidance
-		public IEnumerable<string> CrushClasses { get { return info.CrushClasses; } }
-		
+		public bool CrushableBy(string[] crushClasses, Player owner)
+		{
+			return info.CrushClasses.Intersect(crushClasses).Any();
+		}
+
 		public int2 TopLeft { get { return location; } }
 
 		public IEnumerable<Pair<int2, SubCell>> OccupiedCells() { yield return Pair.New(TopLeft, SubCell.FullCell); }
diff --git a/OpenRA.Mods.RA/Move/Mobile.cs b/OpenRA.Mods.RA/Move/Mobile.cs
index d27c9e2cc0..a3eac5aff1 100755
--- a/OpenRA.Mods.RA/Move/Mobile.cs
+++ b/OpenRA.Mods.RA/Move/Mobile.cs
@@ -91,7 +91,7 @@ namespace OpenRA.Mods.RA.Move
                     return false;
 
                 if (blockingActors.Any(a => !(a.HasTrait<ICrushable>() &&
-                                             a.TraitsImplementing<ICrushable>().Any(b => b.CrushClasses.Intersect(Crushes).Any()))))
+                                             a.TraitsImplementing<ICrushable>().Any(b => b.CrushableBy(Crushes, owner)))))
                     return false;
             }
 
@@ -310,9 +310,9 @@ namespace OpenRA.Mods.RA.Move
 	                // Non-sharable unit can enter a cell with shareable units only if it can crush all of them
 	                if (Info.Crushes == null)
 	                    return false;
-	
-	                if (blockingActors.Any(c => !(c.HasTrait<ICrushable>() &&
-	                                             c.TraitsImplementing<ICrushable>().Any(d => d.CrushClasses.Intersect(Info.Crushes).Any()))))
+
+					if (blockingActors.Any(c => !(c.HasTrait<ICrushable>() &&
+					                              c.TraitsImplementing<ICrushable>().Any(d => d.CrushableBy(Info.Crushes, self.Owner)))))
 	                    return false;
 	            }
 				return true;
@@ -334,7 +334,7 @@ namespace OpenRA.Mods.RA.Move
             var crushable = self.World.ActorMap.GetUnitsAt(toCell).Where(a => a != self && a.HasTrait<ICrushable>());
             foreach (var a in crushable)
             {
-                var crushActions = a.TraitsImplementing<ICrushable>().Where(b => b.CrushClasses.Intersect(Info.Crushes).Any());
+                var crushActions = a.TraitsImplementing<ICrushable>().Where(b => b.CrushableBy(Info.Crushes, self.Owner));
                 foreach (var b in crushActions)
                     b.OnCrush(self);
             }