diff --git a/src/libstd/map.rs b/src/libstd/map.rs
index c7d59aa18cb..d76fd85c587 100644
--- a/src/libstd/map.rs
+++ b/src/libstd/map.rs
@@ -498,7 +498,7 @@ pub fn hash_from_vec<K: Eq IterBytes Hash Const Copy, V: Copy>(
     map
 }
 
-// XXX Transitional
+// FIXME #4431: Transitional
 impl<K: Eq IterBytes Hash Copy, V: Copy> @Mut<LinearMap<K, V>>:
     Map<K, V> {
     pure fn size() -> uint {
diff --git a/src/libstd/workcache.rs b/src/libstd/workcache.rs
index c8898ccd9c7..6b35f3af29a 100644
--- a/src/libstd/workcache.rs
+++ b/src/libstd/workcache.rs
@@ -108,7 +108,7 @@ impl WorkKey {
 type WorkMap = LinearMap<WorkKey, ~str>;
 
 struct Database {
-    // XXX: Fill in.
+    // FIXME #4432: Fill in.
     a: ()
 }
 
@@ -117,7 +117,7 @@ impl Database {
                     _declared_inputs: &const WorkMap,
                     _declared_outputs: &const WorkMap) ->
         Option<(WorkMap, WorkMap, ~str)> {
-        // XXX: load
+        // FIXME #4432: load
         None
     }
     pure fn cache(_fn_name: &str,
@@ -126,12 +126,12 @@ impl Database {
                   _discovered_inputs: &WorkMap,
                   _discovered_outputs: &WorkMap,
                   _result: &str) {
-        // XXX: store
+        // FIXME #4432: store
     }
 }
 
 struct Logger {
-    // XXX: Fill in
+    // FIXME #4432: Fill in
     a: ()
 }
 
@@ -171,7 +171,7 @@ fn digest<T:Encodable<json::Encoder>
             Decodable<json::Decoder>>(t: &T) -> ~str {
     let sha = sha1::sha1();
     let s = do io::with_str_writer |wr| {
-        // XXX: sha1 should be a writer itself, shouldn't
+        // FIXME #4432: sha1 should be a writer itself, shouldn't
         // go via strings.
         t.encode(&json::Encoder(wr));
     };