diff --git a/simulator/datacenter.go b/simulator/datacenter.go
index 41fc56961..7680b602a 100644
--- a/simulator/datacenter.go
+++ b/simulator/datacenter.go
@@ -162,8 +162,10 @@ func (dc *Datacenter) PowerOnMultiVMTask(ctx *Context, req *types.PowerOnMultiVM
 		res.Attempted = []types.ClusterAttemptedVmInfo{}
 
 		for _, ref := range req.Vm {
-			vm := ctx.Map.Get(ref).(*VirtualMachine)
-
+			vm, ok := ctx.Map.Get(ref).(*VirtualMachine)
+			if !ok {
+				continue
+			}
 			// This task creates multiple subtasks which violates the assumption
 			// of 1:1 Context:Task, which results in data races in objects
 			// like the Simulator.Event manager. This is the minimum context
diff --git a/simulator/datacenter_test.go b/simulator/datacenter_test.go
index c6899548e..334b6c1b3 100644
--- a/simulator/datacenter_test.go
+++ b/simulator/datacenter_test.go
@@ -142,7 +142,10 @@ func TestDatacenterPowerOnMultiVMs(t *testing.T) {
 		}
 	}
 
-	dcTask, err := dc.PowerOnVM(ctx, testVMs)
+	// real VC ignores unknown VM refs
+	unknown := types.ManagedObjectReference{Type: "VirtualMachine", Value: "unknown"}
+
+	dcTask, err := dc.PowerOnVM(ctx, append(testVMs, unknown))
 	if err != nil {
 		t.Fatal(err)
 	}