diff --git a/src/librustc/hir/lowering/item.rs b/src/librustc/hir/lowering/item.rs
index 10c2342919ec..2d03e92139e4 100644
--- a/src/librustc/hir/lowering/item.rs
+++ b/src/librustc/hir/lowering/item.rs
@@ -19,7 +19,7 @@ use smallvec::SmallVec;
 use syntax::attr;
 use syntax::ast::*;
 use syntax::visit::{self, Visitor};
-use syntax::source_map::{respan, DesugaringKind, Spanned};
+use syntax::source_map::{respan, DesugaringKind};
 use syntax::symbol::{kw, sym};
 use syntax_pos::Span;
 
@@ -1286,7 +1286,7 @@ impl LoweringContext<'_> {
         hir::FnHeader {
             unsafety: self.lower_unsafety(h.unsafety),
             asyncness: self.lower_asyncness(h.asyncness.node),
-            constness: self.lower_constness(h.constness),
+            constness: h.constness.node,
             abi: self.lower_abi(h.abi),
         }
     }
@@ -1318,13 +1318,6 @@ impl LoweringContext<'_> {
         }
     }
 
-    fn lower_constness(&mut self, c: Spanned<Constness>) -> hir::Constness {
-        match c.node {
-            Constness::Const => hir::Constness::Const,
-            Constness::NotConst => hir::Constness::NotConst,
-        }
-    }
-
     fn lower_asyncness(&mut self, a: IsAsync) -> hir::IsAsync {
         match a {
             IsAsync::Async { .. } => hir::IsAsync::Async,
diff --git a/src/librustc/hir/mod.rs b/src/librustc/hir/mod.rs
index 43f1844b9538..63d4ba6d8b75 100644
--- a/src/librustc/hir/mod.rs
+++ b/src/librustc/hir/mod.rs
@@ -22,7 +22,7 @@ use syntax_pos::{Span, DUMMY_SP, MultiSpan};
 use syntax::source_map::Spanned;
 use syntax::ast::{self, CrateSugar, Ident, Name, NodeId, AsmDialect};
 use syntax::ast::{Attribute, Label, LitKind, StrStyle, FloatTy, IntTy, UintTy};
-pub use syntax::ast::Mutability;
+pub use syntax::ast::{Mutability, Constness};
 use syntax::attr::{InlineAttr, OptimizeAttr};
 use syntax::symbol::{Symbol, kw};
 use syntax::tokenstream::TokenStream;
@@ -2170,12 +2170,6 @@ impl Unsafety {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
-pub enum Constness {
-    Const,
-    NotConst,
-}
-
 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
 pub enum Defaultness {
     Default { has_value: bool },