diff --git a/nova/api/openstack/placement/microversion.py b/nova/api/openstack/placement/microversion.py
index 637ac1a3d69e..da46193d71c2 100644
--- a/nova/api/openstack/placement/microversion.py
+++ b/nova/api/openstack/placement/microversion.py
@@ -87,8 +87,9 @@ def parse_version_string(version_string):
         return Version(*(int(value) for value
                          in version_string.split('.', 1)))
     except (ValueError, TypeError) as exc:
-        raise TypeError('invalid version string: %s; %s' % (
-            version_string, exc))
+        raise TypeError(
+            _('invalid version string: %(version_string)s; %(exc)s') %
+                {'version_string': version_string, 'exc': exc})
 
 
 class MicroversionMiddleware(object):
@@ -178,7 +179,7 @@ def extract_version(headers):
     # version if we really need to.
     if (str(request_version) in VERSIONS and request_version.matches()):
         return request_version
-    raise ValueError('Unacceptable version header: %s' % version_string)
+    raise ValueError(_('Unacceptable version header: %s') % version_string)
 
 
 # From twisted
diff --git a/nova/compute/cells_api.py b/nova/compute/cells_api.py
index 503e284c3e8e..190dbdb4812e 100644
--- a/nova/compute/cells_api.py
+++ b/nova/compute/cells_api.py
@@ -32,6 +32,7 @@ from nova.compute import rpcapi as compute_rpcapi
 from nova.compute import task_states
 from nova.compute import vm_states
 from nova import exception
+from nova.i18n import _
 from nova import objects
 from nova.objects import base as obj_base
 from nova import rpc
@@ -110,7 +111,7 @@ class RPCClientCellsProxy(object):
         version = kwargs.pop('version', None)
 
         if kwargs:
-            raise ValueError("Unsupported kwargs: %s" % kwargs.keys())
+            raise ValueError(_("Unsupported kwargs: %s") % kwargs.keys())
 
         if server:
             ret._server = server
diff --git a/nova/utils.py b/nova/utils.py
index 242bbca36873..7b5d79bfac90 100644
--- a/nova/utils.py
+++ b/nova/utils.py
@@ -296,7 +296,7 @@ def last_completed_audit_period(unit=None, before=None):
     else:
         rightnow = timeutils.utcnow()
     if unit not in ('month', 'day', 'year', 'hour'):
-        raise ValueError('Time period must be hour, day, month or year')
+        raise ValueError(_('Time period must be hour, day, month or year'))
     if unit == 'month':
         if offset == 0:
             offset = 1