diff --git a/pdfminer/pdfparser.py b/pdfminer/pdfparser.py
index ae5fa8d..582eda8 100644
--- a/pdfminer/pdfparser.py
+++ b/pdfminer/pdfparser.py
@@ -120,6 +120,7 @@ class PDFParser(PSStackParser):
                 objlen += len(line)
                 if self.fallback:
                     data += line
+            data = bytes(data)
             self.seek(pos+objlen)
             # XXX limit objlen not to exceed object boundary
             log.debug('Stream: pos=%d, objlen=%d, dic=%r, data=%r...', pos, objlen, dic, data[:10])