diff --git a/gc3libs/backends/openstack.py b/gc3libs/backends/openstack.py
index a3229168..e449c3e8 100755
--- a/gc3libs/backends/openstack.py
+++ b/gc3libs/backends/openstack.py
@@ -932,7 +932,7 @@ def submit_job(self, job):
                 if vm.image['id'] != image_id:
                     continue
                 subresource.submit_job(job)
-                job.execution.instance_id = vm_id
+                job.execution.os_instance_id = vm_id
                 job.changed = True
                 gc3libs.log.info(
                     "Job successfully submitted to remote resource %s.",