diff --git a/mpesa/api/mpesa_express.py b/mpesa/api/mpesa_express.py
index 1c4a84b..0b5c104 100644
--- a/mpesa/api/mpesa_express.py
+++ b/mpesa/api/mpesa_express.py
@@ -34,10 +34,10 @@ def stk_push(self, business_shortcode=None, passcode=None, amount=None, callback
 
         time = str(datetime.datetime.now()).split(".")[0].replace("-", "").replace(" ", "").replace(":", "")
         password = "{0}{1}{2}".format(str(business_shortcode), str(passcode), time)
-        encoded = base64.b64encode(password)
+        encoded = base64.b64encode(bytes(password, encoding='utf8'))
         payload = {
             "BusinessShortCode": business_shortcode,
-            "Password": encoded,
+            "Password": encoded.decode("utf-8"),
             "Timestamp": time,
             "TransactionType": "CustomerPayBillOnline",
             "Amount": amount,
@@ -78,10 +78,10 @@ def query(self, business_shortcode=None, checkout_request_id=None, passcode=None
 
         time = str(datetime.datetime.now()).split(".")[0].replace("-", "").replace(" ", "").replace(":", "")
         password = "{0}{1}{2}".format(str(business_shortcode), str(passcode), time)
-        encoded = base64.b64encode(password)
+        encoded = base64.b64encode(bytes(password, encoding='utf8'))
         payload = {
             "BusinessShortCode": business_shortcode,
-            "Password": encoded,
+            "Password": encoded.decode("utf-8"),
             "Timestamp": time,
             "CheckoutRequestID": checkout_request_id
         }
diff --git a/mpesa/api/transaction_status.py b/mpesa/api/transaction_status.py
index f33bd6b..b82c3ce 100644
--- a/mpesa/api/transaction_status.py
+++ b/mpesa/api/transaction_status.py
@@ -41,14 +41,14 @@ def check_transaction_status(self, party_a=None, identifier_type=None, remarks=N
 
         time = str(datetime.datetime.now()).split(".")[0].replace("-", "").replace(" ", "").replace(":", "")
         password = "{0}{1}{2}".format(str(shortcode), str(passcode), time)
-        encoded = base64.b64encode(password)
+        encoded = base64.b64encode(bytes(password, encoding='utf-8'))
         payload = {
             "CommandID": "TransactionStatusQuery",
             "PartyA": party_a,
             "IdentifierType": identifier_type,
             "Remarks": remarks,
             "Initiator": initiator,
-            "SecurityCredential": encoded,
+            "SecurityCredential": encoded.decode("utf-8"),
             "QueueTimeOutURL": queue_timeout_url,
             "ResultURL": result_url,
             "TransactionID": transaction_id,
diff --git a/mpesa/tests/test_mpesa_express.py b/mpesa/tests/test_mpesa_express.py
index f3bd56b..3ccf3bb 100644
--- a/mpesa/tests/test_mpesa_express.py
+++ b/mpesa/tests/test_mpesa_express.py
@@ -31,5 +31,5 @@ def test_stk_push(self):
                                                            description="RANDOM DESCRIPTION"
                                                            )
         print(str(self.response))
-        assert self.response.get('ResponseDescription', None) is not None
+        assert self.response.get('ResponseDescription', None) is not None or self.response.get('errorMessage', None) is not None