diff --git a/src/librustc/middle/subst.rs b/src/librustc/middle/subst.rs
index 4684bd3532ec1..27e1381735e43 100644
--- a/src/librustc/middle/subst.rs
+++ b/src/librustc/middle/subst.rs
@@ -561,7 +561,18 @@ impl<'a> TypeFolder for SubstFolder<'a> {
             ty::ReEarlyBound(_, space, i, _) => {
                 match self.substs.regions {
                     ErasedRegions => ty::ReStatic,
-                    NonerasedRegions(ref regions) => *regions.get(space, i),
+                    NonerasedRegions(ref regions) =>
+                        match regions.opt_get(space, i) {
+                            Some(t) => *t,
+                            None => {
+                              let span = self.span.unwrap_or(DUMMY_SP);
+                              self.tcx().sess.span_bug(
+                                  span,
+                                  format!("Type parameter out of range \
+                                     when substituting (root type={})",
+                                    self.root_ty.repr(self.tcx())).as_slice());
+                            }
+                        }
                 }
             }
             _ => r
diff --git a/src/librustc/middle/typeck/check/_match.rs b/src/librustc/middle/typeck/check/_match.rs
index 2232cc4965785..91515352576b4 100644
--- a/src/librustc/middle/typeck/check/_match.rs
+++ b/src/librustc/middle/typeck/check/_match.rs
@@ -517,10 +517,8 @@ pub fn check_pat(pcx: &pat_ctxt, pat: &ast::Pat, expected: ty::t) {
             ty::ty_struct(cid, ref substs) => {
                 // Verify that the pattern named the right structure.
                 let item_did = tcx.def_map.borrow().get(&pat.id).def_id();
-                let struct_did =
-                    ty::ty_to_def_id(
-                        ty::lookup_item_type(tcx, item_did).ty).unwrap();
-                if struct_did != cid {
+                match ty::ty_to_def_id(ty::lookup_item_type(tcx, item_did).ty) {
+                  Some(struct_did) if struct_did != cid => {
                     tcx.sess
                        .span_err(path.span,
                                  format!("`{}` does not name the \
@@ -528,6 +526,17 @@ pub fn check_pat(pcx: &pat_ctxt, pat: &ast::Pat, expected: ty::t) {
                                          pprust::path_to_string(path),
                                          fcx.infcx()
                                             .ty_to_string(expected)).as_slice())
+                  },
+                  Some(_) => {},
+                  None => {
+                    tcx.sess.span_bug(
+                      path.span,
+                      format!("This shouldn't happen: failed to lookup structure. \
+                               item_did = {}",
+                              item_did
+                      ).as_slice()
+                    )
+                  },
                 }
 
                 check_struct_pat(pcx, pat.id, pat.span, expected, path,