diff --git a/watcher/decision_engine/model/collector/nova.py b/watcher/decision_engine/model/collector/nova.py
index 157f3b841..55d06c00f 100644
--- a/watcher/decision_engine/model/collector/nova.py
+++ b/watcher/decision_engine/model/collector/nova.py
@@ -337,7 +337,7 @@ class ModelBuilder(object):
         Create an instance node for the graph using nova and the
         `server` nova object.
         :param instance: Nova VM object.
-        :return: A instance node for the graph.
+        :return: An instance node for the graph.
         """
         flavor = instance.flavor
         instance_attributes = {
diff --git a/watcher/decision_engine/model/element/instance.py b/watcher/decision_engine/model/element/instance.py
index c68841f76..5b4dca935 100644
--- a/watcher/decision_engine/model/element/instance.py
+++ b/watcher/decision_engine/model/element/instance.py
@@ -29,7 +29,7 @@ class InstanceState(enum.Enum):
     STOPPED = 'stopped'  # Instance is shut off, the disk image is still there.
     RESCUED = 'rescued'  # A rescue image is running with the original image
     # attached.
-    RESIZED = 'resized'  # a Instance with the new size is active.
+    RESIZED = 'resized'  # an Instance with the new size is active.
 
     SOFT_DELETED = 'soft-delete'
     # still available to restore.