diff --git a/.travis.yml b/.travis.yml
index dadbe57c..6009954f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -29,4 +29,4 @@ notifications:
 #    on_failure: always
 
 after_success:
-  - coveralls
+  - coveralls --base_dir gns3server
diff --git a/gns3server/modules/vpcs/__init__.py b/gns3server/modules/vpcs/__init__.py
index bae14fe1..f79e2b8d 100644
--- a/gns3server/modules/vpcs/__init__.py
+++ b/gns3server/modules/vpcs/__init__.py
@@ -52,7 +52,8 @@ class VPCS(BaseManager):
         vm = self.get_vm(vm_id)
         i = self._used_mac_ids[vm_id]
         self._free_mac_ids[vm.project.id].insert(0, i)
-        del self._used_mac_ids[vm_id]
+        if vm_id in self._used_mac_ids:
+            del self._used_mac_ids[vm_id]
         yield from super().close_vm(vm_id, *args, **kwargs)
         return vm