diff --git a/codegen/build.rs b/codegen/build.rs
index d481e1f9..f2b9f3ba 100644
--- a/codegen/build.rs
+++ b/codegen/build.rs
@@ -8,7 +8,7 @@ use ansi_term::Colour::{Red, Yellow, Blue, White};
 use version_check::{is_nightly, is_min_version, is_min_date};
 
 // Specifies the minimum nightly version needed to compile Rocket's codegen.
-const MIN_DATE: &'static str = "2017-01-03";
+const MIN_DATE: &'static str = "2017-01-31";
 const MIN_VERSION: &'static str = "1.16.0-nightly";
 
 // Convenience macro for writing to stderr.
diff --git a/codegen/src/lints/mod.rs b/codegen/src/lints/mod.rs
index 376634ca..5d53bd88 100644
--- a/codegen/src/lints/mod.rs
+++ b/codegen/src/lints/mod.rs
@@ -190,7 +190,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for RocketLint {
             return;
         }
 
-        if let Some(def_id) = cx.tcx.map.opt_local_def_id(item.id) {
+        if let Some(def_id) = cx.tcx.hir.opt_local_def_id(item.id) {
             self.info_structs.insert(item.name, def_id);
         }
     }