2 files changed, 8 insertions, 2 deletions
diff --git a/opendc-web/opendc-web-ui/src/components/topologies/sidebar/machine/MachineSidebar.js b/opendc-web/opendc-web-ui/src/components/topologies/sidebar/machine/MachineSidebar.js
index 6f89e10b..8a4c33dc 100644
--- a/opendc-web/opendc-web-ui/src/components/topologies/sidebar/machine/MachineSidebar.js
+++ b/opendc-web/opendc-web-ui/src/components/topologies/sidebar/machine/MachineSidebar.js
@@ -15,7 +15,13 @@ import { useSelector } from 'react-redux'
 function MachineSidebar({ tileId, position }) {
     const machine = useSelector(({ topology }) => {
         const rack = topology.racks[topology.tiles[tileId].rack]
-        return topology.machines[rack.machines[position - 1]]
+
+        for (const machineId of rack.machines) {
+            const machine = topology.machines[machineId]
+            if (machine.position === position) {
+                return machine
+            }
+        }
     })
     const machineId = machine.id
     return (
diff --git a/opendc-web/opendc-web-ui/src/components/topologies/sidebar/machine/UnitAddComponent.js b/opendc-web/opendc-web-ui/src/components/topologies/sidebar/machine/UnitAddComponent.js
index 4507b409..18cba23a 100644
--- a/opendc-web/opendc-web-ui/src/components/topologies/sidebar/machine/UnitAddComponent.js
+++ b/opendc-web/opendc-web-ui/src/components/topologies/sidebar/machine/UnitAddComponent.js
@@ -27,7 +27,7 @@ function UnitAddComponent({ units, onAdd }) {
                     </SelectOption>
                 ))}
             </Select>
-            <Button icon={<PlusIcon />} variant="control" onClick={() => onAdd(selected)}>
+            <Button icon={<PlusIcon />} variant="control" onClick={() => onAdd(selected)} isDisabled={!selected}>
                 Add
             </Button>
         </InputGroup>