diff --git a/app/ecs-components/inventory.js b/app/ecs-components/inventory.js
index bf9dd1c..1fa7124 100644
--- a/app/ecs-components/inventory.js
+++ b/app/ecs-components/inventory.js
@@ -65,6 +65,26 @@ export default function(Component) {
         });
         return proxy;
       };
+      Instance.prototype.swapSlots = function(l, r) {
+        const {slots} = this;
+        const tmp = slots[l];
+        const change = {};
+        if (slots[r]) {
+          change[l] = slots[l] = slots[r];
+        }
+        else {
+          change[l] = false;
+          delete slots[l];
+        }
+        if (tmp) {
+          change[r] = slots[r] = tmp;
+        }
+        else {
+          change[r] = false;
+          delete slots[r];
+        }
+        Component.markChange(this.entity, 'slotChange', change);
+      };
       return Instance;
     }
     static schema = new Schema({
diff --git a/app/engine.js b/app/engine.js
index cfa1c36..2c8e9c2 100644
--- a/app/engine.js
+++ b/app/engine.js
@@ -233,6 +233,10 @@ export default class Engine {
           Controlled[payload.type] = payload.value;
           break;
         }
+        case 'swapSlots': {
+          Inventory.swapSlots(...payload.value);
+          break;
+        }
         case 'use': {
           const item = Inventory.item(Wielder.activeSlot + 1);
           if (item) {
diff --git a/app/react-components/ui.jsx b/app/react-components/ui.jsx
index 276108f..0cb51de 100644
--- a/app/react-components/ui.jsx
+++ b/app/react-components/ui.jsx
@@ -180,7 +180,7 @@ export default function Ui({disconnected}) {
             onActivate={(i) => {
               client.send({
                 type: 'Action',
-                payload: {type: 'changeSlot', value: i + 1},
+                payload: {type: 'swapSlots', value: [0, i + 1]},
               });
             }}
             slots={hotbarSlots}