diff --git a/lib/src/index.rs b/lib/src/index.rs
index b2f190225..c32a4cad7 100644
--- a/lib/src/index.rs
+++ b/lib/src/index.rs
@@ -815,16 +815,20 @@ impl<'a> CompositeIndex<'a> {
 
         let mut result = BTreeSet::new();
         while !(items1.is_empty() || items2.is_empty()) {
+            #[allow(unstable_name_collisions)]
             let entry1 = items1.last().unwrap();
+            #[allow(unstable_name_collisions)]
             let entry2 = items2.last().unwrap();
             match entry1.cmp(entry2) {
                 Ordering::Greater => {
+                    #[allow(unstable_name_collisions)]
                     let entry1 = items1.pop_last().unwrap();
                     for parent_entry in entry1.0.parents() {
                         items1.insert(IndexEntryByGeneration(parent_entry));
                     }
                 }
                 Ordering::Less => {
+                    #[allow(unstable_name_collisions)]
                     let entry2 = items2.pop_last().unwrap();
                     for parent_entry in entry2.0.parents() {
                         items2.insert(IndexEntryByGeneration(parent_entry));
@@ -832,7 +836,9 @@ impl<'a> CompositeIndex<'a> {
                 }
                 Ordering::Equal => {
                     result.insert(entry1.0.pos);
+                    #[allow(unstable_name_collisions)]
                     items1.pop_last();
+                    #[allow(unstable_name_collisions)]
                     items2.pop_last();
                 }
             }
diff --git a/lib/src/nightly_shims.rs b/lib/src/nightly_shims.rs
index 6350273ba..97b3e13ad 100644
--- a/lib/src/nightly_shims.rs
+++ b/lib/src/nightly_shims.rs
@@ -85,6 +85,7 @@ impl<K: Ord + Clone> BTreeSetExt<K> for std::collections::BTreeSet<K> {
     }
 
     fn pop_last(&mut self) -> Option<K> {
+        #[allow(unstable_name_collisions)]
         let key = self.last()?;
         let key = key.clone(); // ownership hack
         self.take(&key)