1 files changed, 1 insertions, 1 deletions
diff --git a/class.c b/class.c
index 1ead9b0027..962a9abefc 100644
--- a/class.c
+++ b/class.c
@@ -694,7 +694,7 @@ rb_singleton_class(obj)
 	SPECIAL_SINGLETON(Qnil, rb_cNilClass);
 	SPECIAL_SINGLETON(Qfalse, rb_cFalseClass);
 	SPECIAL_SINGLETON(Qtrue, rb_cTrueClass);
-	rb_bug("unknown immediate %d", obj);
+	rb_bug("unknown immediate %ld", obj);
     }
 
     DEFER_INTS;