diff --git a/src/test/run-pass/small-enum-range-edge.rs b/src/test/run-pass/small-enum-range-edge.rs
index ded66fb86ad..a87a3072c8a 100644
--- a/src/test/run-pass/small-enum-range-edge.rs
+++ b/src/test/run-pass/small-enum-range-edge.rs
@@ -10,6 +10,9 @@
 
 // pretty-expanded FIXME #23616
 
+// this is for the wrapping_add call below.
+#![feature(core)]
+
 /*!
  * Tests the range assertion wraparound case in trans::middle::adt::load_discr.
  */