diff --git a/src/calibre/ebooks/lit/reader.py b/src/calibre/ebooks/lit/reader.py
index 1376363d45..b2effb60b9 100644
--- a/src/calibre/ebooks/lit/reader.py
+++ b/src/calibre/ebooks/lit/reader.py
@@ -217,7 +217,7 @@ class UnBinary(object):
                         state = 'get attr length'
                         continue
                     attr = None
-                    if oc in current_map and current_map[oc]:
+                    if current_map and oc in current_map and current_map[oc]:
                         attr = current_map[oc]
                     elif oc in self.attr_map:
                         attr = self.attr_map[oc]