diff --git a/src/libcore/rt.rs b/src/libcore/rt.rs
index 769c0b3c707..60e6118057d 100644
--- a/src/libcore/rt.rs
+++ b/src/libcore/rt.rs
@@ -62,7 +62,7 @@ pub unsafe fn rt_fail_borrowed() {
     }
 }
 
-// XXX: Make these signatures agree with exchange_alloc's signatures
+// FIXME #4942: Make these signatures agree with exchange_alloc's signatures
 #[rt(exchange_malloc)]
 #[lang="exchange_malloc"]
 pub unsafe fn rt_exchange_malloc(td: *c_char, size: uintptr_t) -> *c_char {
diff --git a/src/libcore/run.rs b/src/libcore/run.rs
index 1761d765838..7a597aa9c75 100644
--- a/src/libcore/run.rs
+++ b/src/libcore/run.rs
@@ -250,7 +250,7 @@ pub fn start_program(prog: &str, args: &[~str]) -> Program {
         r: ProgRepr,
         drop {
             unsafe {
-                // XXX: This is bad.
+                // FIXME #4943: This is bad.
                 destroy_repr(cast::transmute(&self.r));
             }
         }