diff --git a/senlin/common/utils.py b/senlin/common/utils.py
index f84d08e4..acac2cf4 100644
--- a/senlin/common/utils.py
+++ b/senlin/common/utils.py
@@ -168,14 +168,6 @@ def random_name(length=8):
     return lead + tail
 
 
-def format_time(value):
-    """Cut microsecond and format to isoformat string."""
-    if value:
-        value = value.replace(microsecond=0)
-        value = value.isoformat()
-    return value
-
-
 def isotime(at):
     """Stringify time in ISO 8601 format.
 
diff --git a/senlin/engine/cluster.py b/senlin/engine/cluster.py
index 80255243..dd19b84a 100644
--- a/senlin/engine/cluster.py
+++ b/senlin/engine/cluster.py
@@ -208,9 +208,9 @@ class Cluster(object):
             'user': self.user,
             'project': self.project,
             'domain': self.domain,
-            'init_at': utils.format_time(self.init_at),
-            'created_at': utils.format_time(self.created_at),
-            'updated_at': utils.format_time(self.updated_at),
+            'init_at': utils.isotime(self.init_at),
+            'created_at': utils.isotime(self.created_at),
+            'updated_at': utils.isotime(self.updated_at),
             'min_size': self.min_size,
             'max_size': self.max_size,
             'desired_capacity': self.desired_capacity,
diff --git a/senlin/engine/node.py b/senlin/engine/node.py
index f8db002e..76696afc 100644
--- a/senlin/engine/node.py
+++ b/senlin/engine/node.py
@@ -197,9 +197,9 @@ class Node(object):
             'domain': self.domain,
             'index': self.index,
             'role': self.role,
-            'init_at': utils.format_time(self.init_at),
-            'created_at': utils.format_time(self.created_at),
-            'updated_at': utils.format_time(self.updated_at),
+            'init_at': utils.isotime(self.init_at),
+            'created_at': utils.isotime(self.created_at),
+            'updated_at': utils.isotime(self.updated_at),
             'status': self.status,
             'status_reason': self.status_reason,
             'data': self.data,
diff --git a/senlin/engine/receiver.py b/senlin/engine/receiver.py
index 0068d3b1..ab8557dc 100644
--- a/senlin/engine/receiver.py
+++ b/senlin/engine/receiver.py
@@ -175,8 +175,8 @@ class Receiver(object):
             'user': self.user,
             'project': self.project,
             'domain': self.domain,
-            'created_at': utils.format_time(self.created_at),
-            'updated_at': utils.format_time(self.updated_at),
+            'created_at': utils.isotime(self.created_at),
+            'updated_at': utils.isotime(self.updated_at),
             'cluster_id': self.cluster_id,
             'actor': self.actor,
             'action': self.action,
diff --git a/senlin/profiles/base.py b/senlin/profiles/base.py
index 05c05d55..642caae2 100644
--- a/senlin/profiles/base.py
+++ b/senlin/profiles/base.py
@@ -338,8 +338,8 @@ class Profile(object):
             'domain': self.domain,
             'spec': self.spec,
             'metadata': self.metadata,
-            'created_at': utils.format_time(self.created_at),
-            'updated_at': utils.format_time(self.updated_at),
+            'created_at': utils.isotime(self.created_at),
+            'updated_at': utils.isotime(self.updated_at),
         }
         return pb_dict
 
diff --git a/senlin/tests/unit/engine/test_node.py b/senlin/tests/unit/engine/test_node.py
index a415adae..814a1b37 100644
--- a/senlin/tests/unit/engine/test_node.py
+++ b/senlin/tests/unit/engine/test_node.py
@@ -182,9 +182,9 @@ class TestNode(base.SenlinTestCase):
             'domain': node.domain,
             'index': node.index,
             'role': node.role,
-            'init_at': common_utils.format_time(node.init_at),
-            'created_at': common_utils.format_time(node.created_at),
-            'updated_at': common_utils.format_time(node.updated_at),
+            'init_at': common_utils.isotime(node.init_at),
+            'created_at': common_utils.isotime(node.created_at),
+            'updated_at': common_utils.isotime(node.updated_at),
             'status': node.status,
             'status_reason': node.status_reason,
             'data': node.data,
@@ -212,9 +212,9 @@ class TestNode(base.SenlinTestCase):
             'domain': node.domain,
             'index': node.index,
             'role': node.role,
-            'init_at': common_utils.format_time(node.init_at),
-            'created_at': common_utils.format_time(node.created_at),
-            'updated_at': common_utils.format_time(node.updated_at),
+            'init_at': common_utils.isotime(node.init_at),
+            'created_at': common_utils.isotime(node.created_at),
+            'updated_at': common_utils.isotime(node.updated_at),
             'status': node.status,
             'status_reason': node.status_reason,
             'data': node.data,
diff --git a/senlin/tests/unit/engine/test_receiver.py b/senlin/tests/unit/engine/test_receiver.py
index ff0e6931..c160bbbd 100644
--- a/senlin/tests/unit/engine/test_receiver.py
+++ b/senlin/tests/unit/engine/test_receiver.py
@@ -236,8 +236,8 @@ class TestReceiver(base.SenlinTestCase):
             'action': receiver.action,
             'actor': receiver.actor,
             'params': receiver.params,
-            'created_at': common_utils.format_time(receiver.created_at),
-            'updated_at': receiver.updated_at,
+            'created_at': common_utils.isotime(receiver.created_at),
+            'updated_at': common_utils.isotime(receiver.updated_at),
             'channel': None,
         }
 
diff --git a/senlin/tests/unit/profiles/test_profile_base.py b/senlin/tests/unit/profiles/test_profile_base.py
index 1a979ee9..66f3273b 100644
--- a/senlin/tests/unit/profiles/test_profile_base.py
+++ b/senlin/tests/unit/profiles/test_profile_base.py
@@ -672,7 +672,7 @@ class TestProfileBase(base.SenlinTestCase):
             'domain': profile.domain,
             'spec': profile.spec,
             'metadata': profile.metadata,
-            'created_at': common_utils.format_time(profile.created_at),
+            'created_at': common_utils.isotime(profile.created_at),
             'updated_at': None,
         }