diff --git a/netbox_devices.go b/netbox_devices.go
index 6afd797..b461b93 100644
--- a/netbox_devices.go
+++ b/netbox_devices.go
@@ -206,7 +206,7 @@ func (n *NetBox) ListDevices(d *Dcim_Devices_List, f *DeviceFilter) error {
 	deviceurl := n.RootURL + "/api/dcim/devices/"
 	var request *http.Request
 	if len(query) > 0 {
-		deviceurl = deviceurl + query
+		deviceurl = deviceurl + "?" + query
 	}
 	request, err = http.NewRequest("GET", deviceurl, nil)
 	if err != nil {