diff --git a/sakia.spec b/sakia.spec
index 9ab862da24f2eb82078903fef4190a1d33f8c1fa..f3dfc1cf56176e68e6b60d52951abb5d1fcedf72 100644
--- a/sakia.spec
+++ b/sakia.spec
@@ -7,7 +7,7 @@ a = Analysis(['src/sakia/main.py'],
              pathex=['.'],
              binaries=None,
              datas=None,
-             hiddenimports=[],
+             hiddenimports=['six','packaging', 'packaging.version', 'packaging.specifiers'],
              hookspath=['hooks'],
              runtime_hooks=[],
              excludes=[],
diff --git a/src/sakia/core/graph/base_graph.py b/src/sakia/core/graph/base_graph.py
index 6da6f618110f29b3e36db1b1e9cdccbc95426cfb..bc4e53506f4095663daa456c91dd0b06cdbd5b40 100644
--- a/src/sakia/core/graph/base_graph.py
+++ b/src/sakia/core/graph/base_graph.py
@@ -2,8 +2,8 @@ import logging
 import time
 import networkx
 from PyQt5.QtCore import QLocale, QDateTime, QObject
-from sakia.tools.exceptions import NoPeerAvailable
-from sakia.core.net.network import MAX_CONFIRMATIONS
+from ...tools.exceptions import NoPeerAvailable
+from ..net.network import MAX_CONFIRMATIONS
 from .constants import EdgeStatus, NodeStatus
 
 
@@ -107,7 +107,6 @@ class BaseGraph(QObject):
                             QLocale.dateFormat(QLocale(), QLocale.ShortFormat)
                         ),
                         'cert_time': certifier['cert_time'],
-                        'confirmation_text': self.confirmation_text(certifier['block_number'])
                     }
 
                     self.nx_graph.add_edge(certifier['identity'].pubkey, identity.pubkey, attr_dict=arc, weight=len(certifier_list))
@@ -145,7 +144,7 @@ class BaseGraph(QObject):
                             QLocale.dateFormat(QLocale(), QLocale.ShortFormat)
                         ),
                         'cert_time': certified['cert_time'],
-                        'confirmation_text': self.confirmation_text(certified['block_number'])
+                        'confirmation_text': self.confirmation_text(certified['cert_time'])
                     }
 
                     self.nx_graph.add_edge(identity.pubkey, certified['identity'].pubkey, attr_dict=arc,
diff --git a/src/sakia/core/graph/explorer_graph.py b/src/sakia/core/graph/explorer_graph.py
index a34898dbb8ce639a7536edaf3d0c237fcce11d43..687822e6dbab66e351baa0c6dc2841b4c269a346 100644
--- a/src/sakia/core/graph/explorer_graph.py
+++ b/src/sakia/core/graph/explorer_graph.py
@@ -3,7 +3,7 @@ import networkx
 import asyncio
 from PyQt5.QtCore import pyqtSignal
 from .base_graph import BaseGraph
-from sakia.core.graph.constants import EdgeStatus, NodeStatus
+from ..graph.constants import EdgeStatus, NodeStatus
 
 
 class ExplorerGraph(BaseGraph):
@@ -77,24 +77,17 @@ class ExplorerGraph(BaseGraph):
                     logging.debug("New identity explored : {pubkey}".format(pubkey=current_identity.pubkey[:5]))
                     self.graph_changed.emit()
 
-                    certifier_coro = asyncio.ensure_future(current_identity.unique_valid_certifiers_of(self.app.identities_registry,
-                                                                                             self.community))
-
-                    certified_coro = asyncio.ensure_future(current_identity.unique_valid_certified_by(self.app.identities_registry,
-                                                                                            self.community))
-
-                    certifier_list, certified_list = await asyncio.gather(certifier_coro, certified_coro)
-
-                    certifier_coro = asyncio.ensure_future(self.add_certifier_list(certifier_list,
-                                                                                   current_identity, identity))
+                    certifier_list = await current_identity.unique_valid_certifiers_of(self.app.identities_registry,
+                                                                                             self.community)
+                    await self.add_certifier_list(certifier_list, current_identity, identity)
                     logging.debug("New identity certifiers : {pubkey}".format(pubkey=current_identity.pubkey[:5]))
-                    certified_coro = asyncio.ensure_future(self.add_certified_list(certified_list,
-                                                                                   current_identity, identity))
-                    certifier_coro.add_done_callback(lambda f: self.graph_changed.emit())
-                    certified_coro.add_done_callback(lambda f: self.graph_changed.emit())
-                    await asyncio.gather(certifier_coro, certified_coro)
+                    self.graph_changed.emit()
 
+                    certified_list = await current_identity.unique_valid_certified_by(self.app.identities_registry,
+                                                                                            self.community)
+                    await self.add_certified_list(certified_list, current_identity, identity)
                     logging.debug("New identity certified : {pubkey}".format(pubkey=current_identity.pubkey[:5]))
+                    self.graph_changed.emit()
 
                     for cert in certified_list + certifier_list:
                         if cert['identity'] not in explorable[step + 1]:
diff --git a/src/sakia/gui/community_tile.py b/src/sakia/gui/community_tile.py
index 419a476cb233eed149c96a159e03f5932ace3012..1bb65dc008647bcc6cc3b9e2451cf89740b2c4a4 100644
--- a/src/sakia/gui/community_tile.py
+++ b/src/sakia/gui/community_tile.py
@@ -11,7 +11,7 @@ from ucoinpy.documents.block import Block
 
 from ..tools.decorators import asyncify, once_at_a_time, cancel_once_task
 from ..tools.exceptions import NoPeerAvailable
-from sakia.gui.widgets.busy import Busy
+from .widgets.busy import Busy
 
 
 @enum.unique
diff --git a/src/sakia/gui/import_account.py b/src/sakia/gui/import_account.py
index a7ee0dbb1368d95aaa07f5ff506d4999a21b43a5..59d73ff48fd9b2839406094b297ecd2b5c0ed25d 100644
--- a/src/sakia/gui/import_account.py
+++ b/src/sakia/gui/import_account.py
@@ -6,8 +6,8 @@ Created on 22 mai 2014
 import re
 from PyQt5.QtWidgets import QDialog, QDialogButtonBox, QMessageBox, QFileDialog
 
-from sakia.tools.exceptions import Error
-from sakia.gen_resources.import_account_uic import Ui_ImportAccountDialog
+from ..tools.exceptions import Error
+from ..gen_resources.import_account_uic import Ui_ImportAccountDialog
 
 
 class ImportAccountDialog(QDialog, Ui_ImportAccountDialog):
diff --git a/src/sakia/gui/mainwindow.py b/src/sakia/gui/mainwindow.py
index 021e520d03927f4023bd9f8a83c66515be68332c..7d932c2d71ec4d06922fe581af63dea693591dca 100644
--- a/src/sakia/gui/mainwindow.py
+++ b/src/sakia/gui/mainwindow.py
@@ -27,7 +27,7 @@ from ..core import money
 from ..core.community import Community
 from ..tools.decorators import asyncify
 from ..__init__ import __version__
-from sakia.gui.widgets import toast
+from .widgets import toast
 
 
 class MainWindow(QMainWindow, Ui_MainWindow):
diff --git a/src/sakia/gui/process_cfg_community.py b/src/sakia/gui/process_cfg_community.py
index a29e0d7758e724a4e6cd475864f9b5d2583616e9..0622c10d03d81237d331f902b1fab1bf022f80fc 100644
--- a/src/sakia/gui/process_cfg_community.py
+++ b/src/sakia/gui/process_cfg_community.py
@@ -17,7 +17,7 @@ from ..gen_resources.community_cfg_uic import Ui_CommunityConfigurationDialog
 from ..models.peering import PeeringTreeModel
 from ..core import Community
 from ..core.net import Node
-from sakia.gui.widgets import toast
+from .widgets import toast
 from .widgets.dialogs import QAsyncMessageBox
 from ..tools.decorators import asyncify
 
diff --git a/src/sakia/gui/transactions_tab.py b/src/sakia/gui/transactions_tab.py
index 6bb27065ed0a284620eac0957132b5cdd6ea8b58..89ad68fd0746ec4ce93d423f9f1c96b7211de83c 100644
--- a/src/sakia/gui/transactions_tab.py
+++ b/src/sakia/gui/transactions_tab.py
@@ -10,7 +10,7 @@ from ..models.txhistory import HistoryTableModel, TxFilterProxyModel
 from ..tools.exceptions import NoPeerAvailable
 from ..tools.decorators import asyncify, once_at_a_time, cancel_once_task
 from .widgets.context_menu import ContextMenu
-from sakia.gui.widgets import toast
+from .widgets import toast
 
 
 class TransactionsTabWidget(QObject):
diff --git a/src/sakia/gui/transfer.py b/src/sakia/gui/transfer.py
index d57fb4f7c7b90ba01b739f7a69ea1390c25c6be2..7a758ce08db4a232bc5499770836039e8717feb8 100644
--- a/src/sakia/gui/transfer.py
+++ b/src/sakia/gui/transfer.py
@@ -11,8 +11,8 @@ from PyQt5.QtCore import QRegExp, Qt, QObject
 from PyQt5.QtGui import QRegExpValidator
 
 from ..gen_resources.transfer_uic import Ui_TransferMoneyDialog
-from sakia.gui.widgets import toast
-from sakia.gui.widgets.dialogs import QAsyncMessageBox, QMessageBox
+from .widgets import toast
+from .widgets.dialogs import QAsyncMessageBox, QMessageBox
 from ..tools.decorators import asyncify
 
 
diff --git a/src/sakia/gui/views/scenes/wot_scene.py b/src/sakia/gui/views/scenes/wot_scene.py
index e1e187a17a8938e4cfb226d577f3b7ec39cbbfd6..19867adfd96ec93faef180cada137850818dbae3 100644
--- a/src/sakia/gui/views/scenes/wot_scene.py
+++ b/src/sakia/gui/views/scenes/wot_scene.py
@@ -2,8 +2,8 @@ import networkx
 from PyQt5.QtCore import QPoint, pyqtSignal
 from PyQt5.QtWidgets import QGraphicsScene
 
-from sakia.gui.views.edges import WotEdge
-from sakia.gui.views.nodes import WotNode
+from ..edges import WotEdge
+from ..nodes import WotNode
 
 from .base_scene import BaseScene
 
diff --git a/src/sakia/gui/widgets/toast.py b/src/sakia/gui/widgets/toast.py
index c17c32d227f43cd37a3e01ae5247cbcb1ac67750..fd50cf8f8edcb900778f0b2f87c776ba1d4cad78 100644
--- a/src/sakia/gui/widgets/toast.py
+++ b/src/sakia/gui/widgets/toast.py
@@ -8,7 +8,7 @@ import logging
 from PyQt5.QtCore import Qt, QThread
 from PyQt5.QtWidgets import QMainWindow, QApplication
 from PyQt5.QtGui import QImage, QPixmap
-from sakia.gen_resources.toast_uic import Ui_Toast
+from ...gen_resources.toast_uic import Ui_Toast
 
 window = None   # global
 
diff --git a/src/sakia/main.py b/src/sakia/main.py
index 07fc4b845e64dc4dae8b72dcc05130dc6bfe5f9f..1af2b7b2f3408224fdb6fb0aa87938868acc3c12 100755
--- a/src/sakia/main.py
+++ b/src/sakia/main.py
@@ -18,8 +18,8 @@ import PyQt5.QtSvg
 
 from quamash import QSelectorEventLoop
 from PyQt5.QtWidgets import QApplication
-from sakia.gui.mainwindow import MainWindow
-from sakia.core.app import Application
+from .gui.mainwindow import MainWindow
+from .core.app import Application
 
 
 def async_exception_handler(loop, context):