diff --git a/lib/hypervisor/hv_base.py b/lib/hypervisor/hv_base.py
index 44f80e1558516561d8743b7c2389f57453e9f87f..42fd64c913649c903bb4eb391f5a35221ac68258 100644
--- a/lib/hypervisor/hv_base.py
+++ b/lib/hypervisor/hv_base.py
@@ -295,6 +295,17 @@ class BaseHypervisor(object):
     """
     pass
 
+  def BalloonInstanceMemory(self, instance, mem):
+    """Balloon an instance memory to a certain value.
+
+    @type instance: L{objects.Instance}
+    @param instance: instance to be accepted
+    @type mem: int
+    @param mem: actual memory size to use for instance runtime
+
+    """
+    raise NotImplementedError
+
   def FinalizeMigrationDst(self, instance, info, success):
     """Finalize the instance migration on the target node.