diff --git a/eopayment/paybox.py b/eopayment/paybox.py
index cf17ace..a451702 100644
--- a/eopayment/paybox.py
+++ b/eopayment/paybox.py
@@ -22,7 +22,7 @@ import string
 import warnings
 
 from .common import (PaymentCommon, PaymentResponse, FORM, PAID, ERROR, Form,
-        ORDERID_TRANSACTION_SEPARATOR, ResponseError, force_text)
+        ORDERID_TRANSACTION_SEPARATOR, ResponseError, force_text, force_byte)
 
 __all__ = ['sign', 'Payment']
 
@@ -142,7 +142,7 @@ def sign(data, key):
 def verify(data, signature, key=PAYBOX_KEY):
     '''Verify signature using SHA1withRSA by Paybox'''
     key = RSA.importKey(key)
-    h = SHA.new(data)
+    h = SHA.new(force_byte(data))
     verifier = PKCS1_v1_5.new(key)
     return verifier.verify(h, signature)
 
diff --git a/tests/test_paybox.py b/tests/test_paybox.py
index 443d811..1782f4b 100644
--- a/tests/test_paybox.py
+++ b/tests/test_paybox.py
@@ -248,7 +248,7 @@ UX4D2A/QcMvkEcRVXFx5tQqcE9/JnMqE41TF/ebn7jC/MBxxtPFkUN7+EZoeMN7x
 OWzAMDm/xsCWRvvel4GGixgm3aQRUPyTrlm4Ksy32Ya0rNnEDMAvB3dxOn7cp8GR
 ZdzrudBlevZXpr6iYwIDAQAB
 -----END PUBLIC KEY-----'''
-        data = b'coin\n'
+        data = 'coin\n'
         sig64 = '''VCt3sgT0ecacmDEWWNVXJ+jGmIPBMApK42tBJV0FlDjpllOGPy8MsAmLW4/QjTtx
 z0Dkz0NjxvU+5WzQZh9Uuxr/egRCwV4NMRWqu0zaVVioeBvl4/5CWm4f4/1L9+0m
 FBFKOZhgBJnkC+l6+XhT4aYWKaQ4ocmOMV92yjeXTE4='''