diff --git a/api/src/com/cloud/deploy/DeploymentPlanner.java b/api/src/com/cloud/deploy/DeploymentPlanner.java
index c010d5a7ff6..a93b484f771 100644
--- a/api/src/com/cloud/deploy/DeploymentPlanner.java
+++ b/api/src/com/cloud/deploy/DeploymentPlanner.java
@@ -100,6 +100,9 @@ public interface DeploymentPlanner extends Adapter {
         }
         
         public void addPool(long poolId) {
+        	if (_poolIds == null) {
+        		_poolIds = new HashSet<Long>();
+        	}
             _poolIds.add(poolId);
         }