diff --git a/src/librustc/traits/specialize/mod.rs b/src/librustc/traits/specialize/mod.rs
index 8a84fca143809..7e3b00f66e98c 100644
--- a/src/librustc/traits/specialize/mod.rs
+++ b/src/librustc/traits/specialize/mod.rs
@@ -310,6 +310,8 @@ pub(super) fn specialization_graph_provider(
             };
 
             if let Some(overlap) = overlap {
+                debug!("found conflicting implementations {:?}", overlap);
+
                 let msg = format!("conflicting implementations of trait `{}`{}:{}",
                     overlap.trait_desc,
                     overlap.self_desc.clone().map_or(
diff --git a/src/test/ui/traits/reservation-impls/reservation-impl-coherence-conflict.rs b/src/test/ui/traits/reservation-impls/reservation-impl-coherence-conflict.rs
index 775278c30cd4c..538a9e8ce035b 100644
--- a/src/test/ui/traits/reservation-impls/reservation-impl-coherence-conflict.rs
+++ b/src/test/ui/traits/reservation-impls/reservation-impl-coherence-conflict.rs
@@ -4,11 +4,11 @@
 
 #![feature(rustc_attrs)]
 
-trait MyTrait {}
+pub trait MyTrait {}
 #[rustc_reservation_impl="this impl is reserved"]
 impl MyTrait for () {}
 
-trait OtherTrait {}
+pub trait OtherTrait {}
 impl OtherTrait for () {}
 impl<T: MyTrait> OtherTrait for T {}
 //~^ ERROR conflicting implementations