diff --git a/src/test/compile-fail/never-fallback.rs b/src/test/compile-fail/never-fallback.rs
index ca7b715547d2..a43b1a45fe93 100644
--- a/src/test/compile-fail/never-fallback.rs
+++ b/src/test/compile-fail/never-fallback.rs
@@ -30,6 +30,7 @@ impl Flah {
 }
 
 fn doit() -> Result<(), ()> {
+    // The type of _ is unconstrained here and should default to !
     let _ = try!(Flah.flah()); //~ ERROR the trait bound
     Ok(())
 }
diff --git a/src/test/run-pass/unit-fallback.rs b/src/test/run-pass/unit-fallback.rs
index c5c337dc0823..2babc6348e10 100644
--- a/src/test/run-pass/unit-fallback.rs
+++ b/src/test/run-pass/unit-fallback.rs
@@ -27,6 +27,7 @@ impl Flah {
 }
 
 fn doit() -> Result<(), ()> {
+    // The type of _ is unconstrained here and should default to ()
     let _ = try!(Flah.flah());
     Ok(())
 }