diff --git a/converters/base.py b/converters/base.py
index 6ae2033..cc8d0d3 100755
--- a/converters/base.py
+++ b/converters/base.py
@@ -100,7 +100,7 @@ class Converter(object):
     extension = str()
     figures_counter = 0
     infile = str()
-    highlight_source = None
+    highlight_source = True
     infile_dir = str()
     infile_root = str()
     files_dir = str()