diff --git a/src/sakia/core/graph/base_graph.py b/src/sakia/core/graph/base_graph.py
index ee6443bacc72fb264a126f11821f7b97ba9a5782..6da6f618110f29b3e36db1b1e9cdccbc95426cfb 100644
--- a/src/sakia/core/graph/base_graph.py
+++ b/src/sakia/core/graph/base_graph.py
@@ -56,7 +56,7 @@ class BaseGraph(QObject):
             node_status += NodeStatus.OUT
         return node_status
 
-    async def confirmation_text(self, block_number):
+    def confirmation_text(self, block_number):
         """
         Build confirmation text of an arc
         :param int block_number: the block number of the certification
@@ -107,7 +107,7 @@ class BaseGraph(QObject):
                             QLocale.dateFormat(QLocale(), QLocale.ShortFormat)
                         ),
                         'cert_time': certifier['cert_time'],
-                        'confirmation_text': (await self.confirmation_text(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 +145,7 @@ class BaseGraph(QObject):
                             QLocale.dateFormat(QLocale(), QLocale.ShortFormat)
                         ),
                         'cert_time': certified['cert_time'],
-                        'confirmation_text': (await self.confirmation_text(certified['cert_time']))
+                        'confirmation_text': self.confirmation_text(certified['block_number'])
                     }
 
                     self.nx_graph.add_edge(identity.pubkey, certified['identity'].pubkey, attr_dict=arc,
diff --git a/src/sakia/core/net/network.py b/src/sakia/core/net/network.py
index ebaea66b6994b85c959e33e5c4e89882a330da13..320bc435996883bd932202ba5d4c9aa4a79d362a 100644
--- a/src/sakia/core/net/network.py
+++ b/src/sakia/core/net/network.py
@@ -274,9 +274,12 @@ class Network(QObject):
         :return: the number of confirmations of a data
         :rtype: int
         """
-        if block_number > self.current_blockid.number:
-            raise ValueError("Could not compute confirmations : data block number is after current block")
-        return self.current_blockid.number - block_number + 1
+        if block_number:
+            if block_number > self.current_blockid.number:
+                raise ValueError("Could not compute confirmations : data block number is after current block")
+            return self.current_blockid.number - block_number + 1
+        else:
+            return 0
 
     def add_node(self, node):
         """
diff --git a/src/sakia/tests/unit/core/graph/test_base_graph.py b/src/sakia/tests/unit/core/graph/test_base_graph.py
index 56e405533f51c341399a7a3391e9a0b708ac94ed..f7a3bbdd3151a6f0b01e0720b5f033c7b451e710 100644
--- a/src/sakia/tests/unit/core/graph/test_base_graph.py
+++ b/src/sakia/tests/unit/core/graph/test_base_graph.py
@@ -76,10 +76,7 @@ class TestBaseGraph(unittest.TestCase, QuamashTest):
 
         base_graph = BaseGraph(app, community)
 
-        async def exec_test():
-            self.assertEquals((await base_graph.confirmation_text(200)), "2/6")
-
-        self.lp.run_until_complete(exec_test())
+        self.assertEquals(base_graph.confirmation_text(200), "2/6")
 
     @patch('sakia.core.Application')
     @patch('sakia.core.Community')
@@ -89,10 +86,7 @@ class TestBaseGraph(unittest.TestCase, QuamashTest):
 
         base_graph = BaseGraph(app, community)
 
-        async def exec_test():
-            self.assertEquals((await base_graph.confirmation_text(200)), "33 %")
-
-        self.lp.run_until_complete(exec_test())
+        self.assertEquals(base_graph.confirmation_text(200), "33 %")
 
     @patch('sakia.core.Community')
     @patch('sakia.core.Application')