diff --git a/libs/paylib.py b/libs/paylib.py
index c9e7fad..5948ab7 100644
--- a/libs/paylib.py
+++ b/libs/paylib.py
@@ -6,19 +6,19 @@ from natools import fmt, sign, get_privkey
 from gql import gql, Client
 from gql.transport.aiohttp import AIOHTTPTransport
 
-VERSION = "0.1.0"
 PUBKEY_REGEX = "(?![OIl])[1-9A-Za-z]{42,45}"
 
 class Transaction:
 
-    def __init__(self, dunikey, node, recipient, amount, comment='', verbose=False):
+    def __init__(self, dunikey, node, recipient, amount, comment='', useMempool=False, verbose=False):
         self.dunikey = dunikey
         self.recipient = recipient
         self.amount = amount
         self.comment = comment
         self.issuer = get_privkey(dunikey, "pubsec").pubkey
+        self.useMempool = useMempool
         self.verbose = verbose
-        self.isChange = False
+        self._isChange = False
 
         if not re.match(PUBKEY_REGEX, recipient) or len(recipient) > 45:
             sys.stderr.write("La clé publique n'est pas au bon format.\n")
@@ -34,14 +34,15 @@ class Transaction:
 
     def genDoc(self):
         # Build TX generation document
+        print(self.useMempool)
         queryBuild = gql(
             """
-            query ($recipient: String!, $issuer: String!, $amount: Int!, $comment: String!, $isChange: Boolean!){ genTxs(
+            query ($recipient: String!, $issuer: String!, $amount: Int!, $comment: String!, $useMempool: Boolean!){ genTxs(
             amount: $amount
             comment: $comment
             issuer: $issuer
             recipient: $recipient
-            useMempoolSources: $isChange
+            useMempoolSources: $useMempool
             )
         }
         """
@@ -51,7 +52,7 @@ class Transaction:
             "issuer": self.issuer,
             "amount": self.amount,
             "comment": self.comment,
-            "isChange": self.isChange
+            "useMempool": self.useMempool
         }
 
         # Send TX document
@@ -144,6 +145,13 @@ class Transaction:
 
         return txResult
 
+    def _getIsChange(self):
+        return self._isChange
+    def _setIsChange(self, newChange):
+        self._isChange = newChange
+        if newChange: self.useMempool == True
+    isChange = property(_getIsChange, _setIsChange)
+
     def send(self):
         result = self.genDoc()
         result = self.checkTXDoc()
diff --git a/pay.py b/pay.py
index 8f3682c..f39a3f4 100755
--- a/pay.py
+++ b/pay.py
@@ -4,7 +4,9 @@ import sys, argparse, os
 from os.path import join, dirname
 from shutil import copyfile
 from dotenv import load_dotenv
-from libs.paylib import Transaction, VERSION
+from libs.paylib import Transaction
+
+VERSION = "0.1.1"
 
 # Get variables environment
 if not os.path.isfile('.env'):
@@ -23,6 +25,7 @@ parser = argparse.ArgumentParser()
 parser.add_argument('-d', '--destinataire', help="Destinataire du paiement")
 parser.add_argument('-m', '--montant', type=int, help="Montant de la transaction")
 parser.add_argument('-c', '--commentaire',  default="", help="Commentaire de la transaction")
+parser.add_argument('--mempool', action='store_true', help="Utilise les sources en Mempool")
 parser.add_argument('-v', '--verbose', action='store_true', help="Affiche le résultat JSON de la transaction")
 parser.add_argument('--version', action='store_true', help="Affiche la version actuelle du programme")
 args = parser.parse_args()
@@ -37,7 +40,7 @@ if not args.destinataire or not args.montant:
     sys.exit(1)
 
 # Create transaction and send it
-trans = Transaction(dunikey, node, args.destinataire, args.montant, args.commentaire, args.verbose)
+trans = Transaction(dunikey, node, args.destinataire, args.montant, args.commentaire, args.mempool, args.verbose)
 result = trans.send()
 
 if args.verbose: