diff --git a/sword2/http_layer.py b/sword2/http_layer.py
index deb2c25..3c25946 100644
--- a/sword2/http_layer.py
+++ b/sword2/http_layer.py
@@ -85,7 +85,7 @@ def __init__(self, username, password):
         self.password = password
 
     def http_request(self, request):
-        request.add_header(self.auth_header, 'Basic %s' % base64.b64encode(self.username + ':' + self.password))
+        request.add_header(self.auth_header, 'Basic %s' % base64.b64encode((self.username + ':' + self.password).encode()).decode("utf-8"))
         return request
 
     https_request = http_request
diff --git a/sword2/utils.py b/sword2/utils.py
index 46b52ec..bfda645 100644
--- a/sword2/utils.py
+++ b/sword2/utils.py
@@ -188,9 +188,9 @@ def create_multipart_related(payloads):
     """
     # Generate random boundary code
     # TODO check that it does not occur in the payload data
-    bhash = md5(datetime.now().isoformat()).hexdigest()    # eg 'd8bb3ea6f4e0a4b4682be0cfb4e0a24e'
+    bhash = md5(datetime.now().isoformat().encode()).hexdigest()    # eg 'd8bb3ea6f4e0a4b4682be0cfb4e0a24e'
     BOUNDARY = '===========%s_$' % bhash
-    CRLF = '\r\n'   # As some servers might barf without this.
+    CRLF = b'\r\n'   # As some servers might barf without this.
     body = []
     for payload in payloads:   # predicatable ordering...
         body.append('--' + BOUNDARY)
@@ -213,17 +213,20 @@ def create_multipart_related(payloads):
             body.append('Content-Transfer-Encoding: base64')
             body.append('')
             if hasattr(payload['data'], 'read'):
-                body.append(b64encode(payload['data'].read()))
+                body.append(b64encode(payload['data'].read()).decode())
             else:
-                body.append(b64encode(payload['data']))
+                body.append(b64encode(payload['data']).decode())
         else:
             body.append('')
             if hasattr(payload['data'], 'read'):
-                body.append(b64encode(payload['data'].read()))
+                body.append(b64encode(payload['data'].read()).decode())
             else:
-                body.append(b64encode(payload['data']))
+                try:
+                    body.append(b64encode(payload['data']).decode())
+                except TypeError:
+                    body.append(b64encode(payload['data'].encode("utf-8")).decode())
     body.append('--' + BOUNDARY + '--')
     body.append('')
-    body_bytes = CRLF.join(body)
+    body_bytes = CRLF.join([line.encode("utf-8") for line in body])
     content_type = 'multipart/related; boundary="%s"' % BOUNDARY
     return content_type, body_bytes