diff --git a/duct.py b/duct.py
index <HASH>..<HASH> 100644
--- a/duct.py
+++ b/duct.py
@@ -78,8 +78,8 @@ class CheckedError(subprocess.CalledProcessError):
         self.expression = expression
 
     def __str__(self):
-        return 'Expression {0} returned non-zero exit status {1}.'.format(
-            self.expression, self.result.returncode)
+        return 'Expression {0} returned non-zero exit status: {1}'.format(
+            self.expression, self.result)
 
 
 # Implementation Details
include captured output in CheckedError's repr

I suspect CI is failing because of a PYTHONPATH issue, but it's hard to
tell because I'm not seeing captured output in my errors. This should
fix the issue.