diff --git a/src/librustc_middle/ty/consts/kind.rs b/src/librustc_middle/ty/consts/kind.rs
index d1deea4a90e..75287ff7dac 100644
--- a/src/librustc_middle/ty/consts/kind.rs
+++ b/src/librustc_middle/ty/consts/kind.rs
@@ -87,8 +87,8 @@ pub fn eval(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Self {
 
     #[inline]
     /// Tries to evaluate the constant if it is `Unevaluated`. If that isn't possible or necessary
-    // return None
-    pub fn try_eval(
+    /// return `None`.
+    pub(super) fn try_eval(
         self,
         tcx: TyCtxt<'tcx>,
         param_env: ParamEnv<'tcx>,