Index: binaries/data/mods/public/simulation/components/UnitAI.js
===================================================================
--- binaries/data/mods/public/simulation/components/UnitAI.js
+++ binaries/data/mods/public/simulation/components/UnitAI.js
@@ -533,6 +533,33 @@
 	},
 
 	"Order.Gather": function(msg) {
+		if (!this.CanGather(this.order.data.target))
+		{
+			this.SetNextState("INDIVIDUAL.GATHER.FINDINGNEWTARGET");
+			return;
+		}
+
+		// If the unit is full go to the nearest dropsite instead of trying to gather.
+		// Unless our target is a treasure which we cannot be full enough with (we can't carry treasures).
+		let cmpResourceGatherer = Engine.QueryInterface(this.entity, IID_ResourceGatherer);
+		if (msg.data.type.generic !== "treasure" && cmpResourceGatherer && !cmpResourceGatherer.CanCarryMore(msg.data.type.generic))
+		{
+			let nearestDropsite = this.FindNearestDropsite(msg.data.type.generic);
+			// Oh no, couldn't find any dropsites. Give up on gathering.
+			if (!nearestDropsite)
+			{
+				this.FinishOrder();
+				return;
+			}
+
+			this.PushOrderFront("ReturnResource", {
+				"target": nearestDropsite,
+				"force": false,
+				"type": msg.data.type
+			});
+			return;
+		}
+
 		// If the target is still alive, we need to kill it first
 		if (this.MustKillGatherTarget(this.order.data.target))
 		{