diff --git a/oletools/rtfobj.py b/oletools/rtfobj.py
index 9060aa5..f78330e 100644
--- a/oletools/rtfobj.py
+++ b/oletools/rtfobj.py
@@ -84,8 +84,9 @@ http://www.decalage.info/python/oletools
 # 2018-04-27       PL: - extract and display the CLSID of OLE objects
 # 2018-04-30       PL: - handle "\'" obfuscation trick - issue #281
 # 2018-05-10       PL: - fixed issues #303 #307: several destination cwords were incorrect
+# 2018-05-17       PL: - fixed issue #273: bytes constants instead of str
 
-__version__ = '0.53dev9'
+__version__ = '0.53dev11'
 
 # ------------------------------------------------------------------------------
 # TODO:
@@ -701,7 +702,7 @@ class RtfObjParser(RtfParser):
                 log.debug('*** Not an OLE 1.0 Object')
 
     def bin(self, bindata):
-        if self.current_destination.cword == 'objdata':
+        if self.current_destination.cword == b'objdata':
             # TODO: keep track of this, because it is unusual and indicates potential obfuscation
             # trick: hexlify binary data, add it to hex data
             self.current_destination.data += binascii.hexlify(bindata)
@@ -723,7 +724,7 @@ class RtfObjParser(RtfParser):
             # print(hexdigits)
             # move the index two bytes forward
             self.index += 2
-            if self.current_destination.cword == 'objdata':
+            if self.current_destination.cword == b'objdata':
                 # Here's the tricky part: there is a bug in the MS Word RTF parser at least
                 # until Word 2016, that removes the last hex digit before the \'hh control
                 # symbol, ONLY IF the number of hex digits read so far is odd.
@@ -888,7 +889,7 @@ def process_file(container, filename, data, output_dir=None, save_object=False):
                     ole_color = 'red'
             # Detect OLE2Link exploit
             # http://www.kb.cert.org/vuls/id/921560
-            if rtfobj.class_name == 'OLE2Link':
+            if rtfobj.class_name == b'OLE2Link':
                 ole_color = 'red'
                 ole_column += '\nPossibly an exploit for the OLE2Link vulnerability (VU#921560, CVE-2017-0199)'
         else:
diff --git a/setup.py b/setup.py
index 203a354..ebf14c9 100644
--- a/setup.py
+++ b/setup.py
@@ -43,7 +43,7 @@ import os, fnmatch
 #--- METADATA -----------------------------------------------------------------
 
 name         = "oletools"
-version      = '0.53dev10'
+version      = '0.53dev11'
 desc         = "Python tools to analyze security characteristics of MS Office and OLE files (also called Structured Storage, Compound File Binary Format or Compound Document File Format), for Malware Analysis and Incident Response #DFIR"
 long_desc    = open('oletools/README.rst').read()
 author       = "Philippe Lagadec"