diff --git a/sith.py b/sith.py
index 2f676220..ab2ba293 100755
--- a/sith.py
+++ b/sith.py
@@ -149,7 +149,7 @@ class TestCase(object):
         # Three lines ought to be enough
         lower = lineno - show if lineno - show > 0 else 0
         prefix = '  |'
-        for i, line in enumerate(self.script.source.split('\n')[lower:lineno]):
+        for i, line in enumerate(self.script._source.split('\n')[lower:lineno]):
             print(prefix, lower + i + 1, line)
         print(prefix, '   ', ' ' * (column + len(str(lineno))), '^')