diff --git a/src/librustc/ich/hcx.rs b/src/librustc/ich/hcx.rs
index aade4c3f74c54..76e4b5f01b775 100644
--- a/src/librustc/ich/hcx.rs
+++ b/src/librustc/ich/hcx.rs
@@ -249,6 +249,12 @@ impl<'a> rustc_span::HashStableContext for StableHashingContext<'a> {
         self.hash_spans
     }
 
+    #[inline]
+    fn hash_def_id(&mut self, def_id: DefId, hasher: &mut StableHasher) {
+        let hcx = self;
+        hcx.def_path_hash(def_id).hash_stable(hcx, hasher);
+    }
+
     fn byte_pos_to_line_and_col(
         &mut self,
         byte: BytePos,
diff --git a/src/librustc/ich/impls_hir.rs b/src/librustc/ich/impls_hir.rs
index 0155861549773..625d8a4670f22 100644
--- a/src/librustc/ich/impls_hir.rs
+++ b/src/librustc/ich/impls_hir.rs
@@ -11,12 +11,6 @@ use smallvec::SmallVec;
 use std::mem;
 
 impl<'ctx> rustc_hir::HashStableContext for StableHashingContext<'ctx> {
-    #[inline]
-    fn hash_def_id(&mut self, def_id: DefId, hasher: &mut StableHasher) {
-        let hcx = self;
-        hcx.def_path_hash(def_id).hash_stable(hcx, hasher);
-    }
-
     #[inline]
     fn hash_hir_id(&mut self, hir_id: hir::HirId, hasher: &mut StableHasher) {
         let hcx = self;
diff --git a/src/librustc_hir/lib.rs b/src/librustc_hir/lib.rs
index f54fa291bd6e8..e4edd34bd6e23 100644
--- a/src/librustc_hir/lib.rs
+++ b/src/librustc_hir/lib.rs
@@ -12,7 +12,7 @@
 extern crate rustc_data_structures;
 
 pub mod def;
-pub mod def_id;
+pub use rustc_span::def_id;
 mod hir;
 pub mod hir_id;
 pub mod intravisit;
diff --git a/src/librustc_hir/stable_hash_impls.rs b/src/librustc_hir/stable_hash_impls.rs
index 294074cd3e5a4..e8407b537011b 100644
--- a/src/librustc_hir/stable_hash_impls.rs
+++ b/src/librustc_hir/stable_hash_impls.rs
@@ -1,6 +1,5 @@
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 
-use crate::def_id::DefId;
 use crate::hir::{BodyId, Expr, ImplItemId, ItemId, Mod, TraitItemId, Ty, VisibilityKind};
 use crate::hir_id::HirId;
 
@@ -8,7 +7,6 @@ use crate::hir_id::HirId;
 /// This is a hack to allow using the `HashStable_Generic` derive macro
 /// instead of implementing everything in librustc.
 pub trait HashStableContext: syntax::HashStableContext + rustc_target::HashStableContext {
-    fn hash_def_id(&mut self, _: DefId, hasher: &mut StableHasher);
     fn hash_hir_id(&mut self, _: HirId, hasher: &mut StableHasher);
     fn hash_body_id(&mut self, _: BodyId, hasher: &mut StableHasher);
     fn hash_reference_to_item(&mut self, _: HirId, hasher: &mut StableHasher);
@@ -24,12 +22,6 @@ impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for HirId {
     }
 }
 
-impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for DefId {
-    fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
-        hcx.hash_def_id(*self, hasher)
-    }
-}
-
 impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for BodyId {
     fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
         hcx.hash_body_id(*self, hasher)
diff --git a/src/librustc_hir/def_id.rs b/src/librustc_span/def_id.rs
similarity index 95%
rename from src/librustc_hir/def_id.rs
rename to src/librustc_span/def_id.rs
index 7ee778ddd8ec7..6cdfd0500ca84 100644
--- a/src/librustc_hir/def_id.rs
+++ b/src/librustc_span/def_id.rs
@@ -1,3 +1,5 @@
+use crate::HashStableContext;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::AtomicRef;
 use rustc_index::vec::Idx;
 use rustc_serialize::{Decoder, Encoder};
@@ -18,15 +20,6 @@ pub enum CrateNum {
     Index(CrateId),
 }
 
-impl ::std::fmt::Debug for CrateNum {
-    fn fmt(&self, fmt: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
-        match self {
-            CrateNum::Index(id) => write!(fmt, "crate{}", id.private),
-            CrateNum::ReservedForIncrCompCache => write!(fmt, "crate for decoding incr comp cache"),
-        }
-    }
-}
-
 /// Item definitions in the currently-compiled crate would have the `CrateNum`
 /// `LOCAL_CRATE` in their `DefId`.
 pub const LOCAL_CRATE: CrateNum = CrateNum::Index(CrateId::from_u32_const(0));
@@ -100,6 +93,15 @@ impl rustc_serialize::UseSpecializedDecodable for CrateNum {
     }
 }
 
+impl ::std::fmt::Debug for CrateNum {
+    fn fmt(&self, fmt: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
+        match self {
+            CrateNum::Index(id) => write!(fmt, "crate{}", id.private),
+            CrateNum::ReservedForIncrCompCache => write!(fmt, "crate for decoding incr comp cache"),
+        }
+    }
+}
+
 rustc_index::newtype_index! {
     /// A DefIndex is an index into the hir-map for a crate, identifying a
     /// particular definition. It should really be considered an interned
@@ -207,3 +209,9 @@ impl fmt::Debug for LocalDefId {
 
 impl rustc_serialize::UseSpecializedEncodable for LocalDefId {}
 impl rustc_serialize::UseSpecializedDecodable for LocalDefId {}
+
+impl<CTX: HashStableContext> HashStable<CTX> for DefId {
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
+        hcx.hash_def_id(*self, hasher)
+    }
+}
diff --git a/src/librustc_span/lib.rs b/src/librustc_span/lib.rs
index ac9c3360b860d..b7c6b0c4f690e 100644
--- a/src/librustc_span/lib.rs
+++ b/src/librustc_span/lib.rs
@@ -22,7 +22,8 @@ use edition::Edition;
 pub mod hygiene;
 use hygiene::Transparency;
 pub use hygiene::{DesugaringKind, ExpnData, ExpnId, ExpnKind, MacroKind, SyntaxContext};
-
+pub mod def_id;
+use def_id::DefId;
 mod span_encoding;
 pub use span_encoding::{Span, DUMMY_SP};
 
@@ -1558,6 +1559,7 @@ fn lookup_line(lines: &[BytePos], pos: BytePos) -> isize {
 /// instead of implementing everything in librustc.
 pub trait HashStableContext {
     fn hash_spans(&self) -> bool;
+    fn hash_def_id(&mut self, _: DefId, hasher: &mut StableHasher);
     fn byte_pos_to_line_and_col(
         &mut self,
         byte: BytePos,