diff --git a/src/hubs/basehub.ts b/src/hubs/basehub.ts
index 90a8aba..75e313e 100644
--- a/src/hubs/basehub.ts
+++ b/src/hubs/basehub.ts
@@ -360,7 +360,8 @@ export class BaseHub extends EventEmitter {
             const device = this._createDevice(deviceType, portId);
             this._attachDevice(device);
             return device;
-        } else {
+        }
+        else if (deviceType) {
             if (this._attachedDevices[portId].type === deviceType) {
                 debug(`Device of ${deviceType} already attached to portId ${portId}, returning existing device`);
                 return this._attachedDevices[portId];
@@ -368,6 +369,9 @@ export class BaseHub extends EventEmitter {
                 throw new Error(`Already a different type of device attached to portId ${portId}. Only use this method when you are certain what's attached.`);
             }
         }
+        else {
+            this._detachDevice(this._attachedDevices[portId]);
+        }
     }