diff --git a/ryu/tests/test_lib.py b/ryu/tests/test_lib.py
index c812daff..97315662 100644
--- a/ryu/tests/test_lib.py
+++ b/ryu/tests/test_lib.py
@@ -182,7 +182,7 @@ class RyuTestResult(result.TextTestResult):
                 if stream is not None:
                     if self.showAll:
                         message = [label]
-                        detail = result._exception_details(err[1])
+                        detail = result._exception_detail(err[1])
                         if detail:
                             message.append(detail)
                         stream.writeln(": ".join(message))