diff --git a/src/librustc/hir/def_id.rs b/src/librustc/hir/def_id.rs
index 7f76e1bf770bf..78daff9f67aa5 100644
--- a/src/librustc/hir/def_id.rs
+++ b/src/librustc/hir/def_id.rs
@@ -93,10 +93,19 @@ impl serialize::UseSpecializedDecodable for CrateNum {
 ///
 /// Since the DefIndex is mostly treated as an opaque ID, you probably
 /// don't have to care about these ranges.
-#[derive(Clone, Debug, Eq, Ord, PartialOrd, PartialEq, RustcEncodable,
+#[derive(Clone, Eq, Ord, PartialOrd, PartialEq, RustcEncodable,
            RustcDecodable, Hash, Copy)]
 pub struct DefIndex(u32);
 
+impl fmt::Debug for DefIndex {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f,
+               "DefIndex({}:{})",
+               self.address_space().index(),
+               self.as_array_index())
+    }
+}
+
 impl DefIndex {
     #[inline]
     pub fn new(x: usize) -> DefIndex {
diff --git a/src/test/mir-opt/validate_1.rs b/src/test/mir-opt/validate_1.rs
index ae9dcf8b7352d..f9833ffecc280 100644
--- a/src/test/mir-opt/validate_1.rs
+++ b/src/test/mir-opt/validate_1.rs
@@ -30,7 +30,7 @@ fn main() {
 // END RUST SOURCE
 // START rustc.node12.EraseRegions.after.mir
 //     bb0: {
-//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(5) => validate_1/8cd878b::{{impl}}[0]::foo[0] }, BrAnon(0)) Test, _2: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(5) => validate_1/8cd878b::{{impl}}[0]::foo[0] }, BrAnon(1)) mut i32]);
+//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(0:5) => validate_1/8cd878b::{{impl}}[0]::foo[0] }, BrAnon(0)) Test, _2: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(0:5) => validate_1/8cd878b::{{impl}}[0]::foo[0] }, BrAnon(1)) mut i32]);
 //         return;
 //     }
 // END rustc.node12.EraseRegions.after.mir
@@ -57,7 +57,7 @@ fn main() {
 // START rustc.node50.EraseRegions.after.mir
 // fn main::{{closure}}(_1: &ReErased [closure@NodeId(50)], _2: &ReErased mut i32) -> i32 {
 //     bb0: {
-//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(2147483663) => validate_1/8cd878b::main[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(50)], _2: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(2147483663) => validate_1/8cd878b::main[0]::{{closure}}[0] }, BrAnon(1)) mut i32]);
+//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(1:15) => validate_1/8cd878b::main[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(50)], _2: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(1:15) => validate_1/8cd878b::main[0]::{{closure}}[0] }, BrAnon(1)) mut i32]);
 //         StorageLive(_3);
 //         _3 = _2;
 //         StorageLive(_4);
diff --git a/src/test/mir-opt/validate_4.rs b/src/test/mir-opt/validate_4.rs
index 2ee459d6809c5..cd5beae8e91fb 100644
--- a/src/test/mir-opt/validate_4.rs
+++ b/src/test/mir-opt/validate_4.rs
@@ -48,8 +48,8 @@ fn main() {
 // START rustc.node22.EraseRegions.after.mir
 // fn write_42::{{closure}}(_1: &ReErased [closure@NodeId(22)], _2: *mut i32) -> () {
 //     bb0: {
-//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(2147483659) => validate_4/8cd878b::write_42[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(22)], _2: *mut i32]);
-//         Validate(Release, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(2147483659) => validate_4/8cd878b::write_42[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(22)], _2: *mut i32]);
+//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(1:11) => validate_4/8cd878b::write_42[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(22)], _2: *mut i32]);
+//         Validate(Release, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(1:11) => validate_4/8cd878b::write_42[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(22)], _2: *mut i32]);
 //         StorageLive(_3);
 //         _3 = _2;
 //         (*_3) = const 23i32;
@@ -61,8 +61,8 @@ fn main() {
 // START rustc.node31.EraseRegions.after.mir
 // fn test(_1: &ReErased mut i32) -> () {
 //     bb0: {
-//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(4) => validate_4/8cd878b::test[0] }, BrAnon(0)) mut i32]);
-//         Validate(Release, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(4) => validate_4/8cd878b::test[0] }, BrAnon(0)) mut i32]);
+//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(0:4) => validate_4/8cd878b::test[0] }, BrAnon(0)) mut i32]);
+//         Validate(Release, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(0:4) => validate_4/8cd878b::test[0] }, BrAnon(0)) mut i32]);
 //         _3 = const write_42(_4) -> bb1;
 //     }
 //     bb1: {
@@ -74,8 +74,8 @@ fn main() {
 // START rustc.node60.EraseRegions.after.mir
 // fn main::{{closure}}(_1: &ReErased [closure@NodeId(60)], _2: &ReErased mut i32) -> bool {
 //     bb0: {
-//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(2147483663) => validate_4/8cd878b::main[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(60)], _2: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(2147483663) => validate_4/8cd878b::main[0]::{{closure}}[0] }, BrAnon(1)) mut i32]);
-//         Validate(Release, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(2147483663) => validate_4/8cd878b::main[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(60)], _2: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(2147483663) => validate_4/8cd878b::main[0]::{{closure}}[0] }, BrAnon(1)) mut i32]);
+//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(1:15) => validate_4/8cd878b::main[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(60)], _2: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(1:15) => validate_4/8cd878b::main[0]::{{closure}}[0] }, BrAnon(1)) mut i32]);
+//         Validate(Release, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(1:15) => validate_4/8cd878b::main[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(60)], _2: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(1:15) => validate_4/8cd878b::main[0]::{{closure}}[0] }, BrAnon(1)) mut i32]);
 //         StorageLive(_3);
 //         _0 = const write_42(_4) -> bb1;
 //     }
diff --git a/src/test/mir-opt/validate_5.rs b/src/test/mir-opt/validate_5.rs
index ef2073dcc4b0f..dc3daee7ad3a4 100644
--- a/src/test/mir-opt/validate_5.rs
+++ b/src/test/mir-opt/validate_5.rs
@@ -36,7 +36,7 @@ fn main() {
 // START rustc.node17.EraseRegions.after.mir
 // fn test(_1: &ReErased mut i32) -> () {
 //     bb0: {
-//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(4) => validate_5/8cd878b::test[0] }, BrAnon(0)) mut i32]);
+//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(0:4) => validate_5/8cd878b::test[0] }, BrAnon(0)) mut i32]);
 //         Validate(Release, [_3: bool, _4: *mut i32]);
 //         _3 = const write_42(_4) -> bb1;
 //     }
@@ -45,7 +45,7 @@ fn main() {
 // START rustc.node46.EraseRegions.after.mir
 // fn main::{{closure}}(_1: &ReErased [closure@NodeId(46)], _2: &ReErased mut i32) -> bool {
 //     bb0: {
-//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(2147483660) => validate_5/8cd878b::main[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(46)], _2: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(2147483660) => validate_5/8cd878b::main[0]::{{closure}}[0] }, BrAnon(1)) mut i32]);
+//         Validate(Acquire, [_1: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(1:12) => validate_5/8cd878b::main[0]::{{closure}}[0] }, "BrEnv") [closure@NodeId(46)], _2: &ReFree(DefId { krate: CrateNum(0), node: DefIndex(1:12) => validate_5/8cd878b::main[0]::{{closure}}[0] }, BrAnon(1)) mut i32]);
 //         StorageLive(_3);
 //         _3 = _2;
 //         StorageLive(_4);