1 files changed, 1 insertions, 0 deletions
diff --git a/error.c b/error.c
index edf0b16e2b..936079a659 100644
--- a/error.c
+++ b/error.c
@@ -309,6 +309,7 @@ exc_initialize(argc, argv, exc)
 	StringValue(mesg);	/* ensure mesg can be converted to String */
     }
     rb_iv_set(exc, "mesg", mesg);
+    rb_iv_set(exc, "bt", Qnil);
 
     return exc;
 }