diff --git a/src/collector/mod.rs b/src/collector/mod.rs
index f64df3cde..1f43851a9 100644
--- a/src/collector/mod.rs
+++ b/src/collector/mod.rs
@@ -93,6 +93,7 @@ mod tests {
 
     use super::*;
     use test::Bencher;
+    use ScoredDoc;
 
     #[bench]
     fn build_collector(b: &mut Bencher) {
@@ -100,7 +101,7 @@ mod tests {
             let mut count_collector = CountCollector::new();
             let docs: Vec<u32> = (0..1_000_000).collect();
             for doc in docs {
-                count_collector.collect(doc, 1f32);
+                count_collector.collect(ScoredDoc(1f32, doc));
             }
             count_collector.count()
         });
diff --git a/src/compression/simdcomp.rs b/src/compression/simdcomp.rs
index a6512c0eb..f40d5c694 100644
--- a/src/compression/simdcomp.rs
+++ b/src/compression/simdcomp.rs
@@ -199,7 +199,7 @@ mod tests {
             assert_eq!(remaining_data.len(), 0);
         }
         for i in 0..128 {
-            assert_eq!(vals[i], decoder.output()[i]);
+            assert_eq!(vals[i], decoder.output(i));
         }
     }
 
@@ -214,7 +214,7 @@ mod tests {
             assert_eq!(remaining_data.len(), 0);
         }
         for i in 0..128 {
-            assert_eq!(vals[i], decoder.output()[i]);
+            assert_eq!(vals[i], decoder.output(i));
         }
     }
     
@@ -234,7 +234,7 @@ mod tests {
             assert_eq!(remaining_data[0], 173u8);
         }
         for i in 0..n {
-            assert_eq!(vals[i], decoder.output()[i]);
+            assert_eq!(vals[i], decoder.output(i));
         }
     }
 
@@ -254,7 +254,7 @@ mod tests {
             assert_eq!(remaining_data[0], 173u8);
         }
         for i in 0..n {
-            assert_eq!(vals[i], decoder.output()[i]);
+            assert_eq!(vals[i], decoder.output(i));
         }
     }
     
@@ -274,7 +274,7 @@ mod tests {
                 let mut decoder = SIMDBlockDecoder::new();
                 let remaining_data = decoder.uncompress_vint_sorted(&encoded_data, *offset, input.len());
                 assert_eq!(0, remaining_data.len());
-                for (&decoded, &expected) in decoder.output().iter().zip(input.iter()) {
+                for (&decoded, &expected) in decoder.output_array().iter().zip(input.iter()) {
                     assert_eq!(decoded, expected);
                 }
             }
diff --git a/src/core/index.rs b/src/core/index.rs
index 38e6be78b..f083a04a9 100644
--- a/src/core/index.rs
+++ b/src/core/index.rs
@@ -15,7 +15,7 @@ use num_cpus;
 use core::segment_serializer::SegmentSerializer;
 
 
-#[derive(Clone, PartialEq, Eq, Hash,RustcDecodable,RustcEncodable)]
+#[derive(Clone, Copy, PartialEq, Eq, Hash,RustcDecodable,RustcEncodable)]
 pub struct SegmentId(Uuid);
 
 impl SegmentId {
@@ -48,6 +48,12 @@ impl IndexMeta {
             schema: schema,
         }
     }
+
+    fn segment_ordinal(&self, segment_id: SegmentId) -> Option<usize> {
+        self.segments
+            .iter()
+            .position(|&el| el == segment_id)
+    }
 }
 
 impl fmt::Debug for Index {
@@ -147,10 +153,8 @@ impl Index {
     pub fn publish_merge_segment(&mut self, segments: &Vec<Segment>, merged_segment: &Segment) -> io::Result<()> {
         {
             let mut meta_write = self.metas.write().unwrap();
-            for segment in segments.iter() {
-                let segment_pos = meta_write
-                    .segments.iter()
-                    .position(|el| *el == segment.id());
+            for segment in segments {
+                let segment_pos = meta_write.segment_ordinal(segment.id());
                 match segment_pos {
                     Some(pos) => {
                         meta_write.segments.remove(pos);
@@ -176,17 +180,16 @@ impl Index {
     }
 
     pub fn segments(&self,) -> Vec<Segment> {
-        // TODO handle error
         self.segment_ids()
             .into_iter()
-            .map(|segment_id| self.segment(&segment_id))
+            .map(|segment_id| self.segment(segment_id))
             .collect()
     }
 
-    pub fn segment(&self, segment_id: &SegmentId) -> Segment {
+    pub fn segment(&self, segment_id: SegmentId) -> Segment {
         Segment {
             index: self.clone(),
-            segment_id: segment_id.clone()
+            segment_id: segment_id
         }
     }
 
@@ -201,7 +204,7 @@ impl Index {
     }
 
     pub fn new_segment(&self,) -> Segment {
-        self.segment(&SegmentId::new())
+        self.segment(SegmentId::new())
     }
 
     pub fn load_metas(&mut self,) -> io::Result<()> {
@@ -262,7 +265,7 @@ impl Segment {
     }
 
     pub fn id(&self,) -> SegmentId {
-        self.segment_id.clone()
+        self.segment_id
     }
 
     fn path_suffix(component: &SegmentComponent)-> &'static str {
diff --git a/src/core/merger.rs b/src/core/merger.rs
index c78b56121..c2d6d21c3 100644
--- a/src/core/merger.rs
+++ b/src/core/merger.rs
@@ -226,7 +226,7 @@ mod tests {
     use schema::Document;
     use schema::Term;
     use core::index::Index;
-    use core::searcher::DocAddress;
+    use DocAddress;
     use collector::FastFieldTestCollector;
     use collector::TestCollector;
     use query::MultiTermQuery;
diff --git a/src/core/segment_writer.rs b/src/core/segment_writer.rs
index 375ec5808..5f90bcafd 100644
--- a/src/core/segment_writer.rs
+++ b/src/core/segment_writer.rs
@@ -41,7 +41,8 @@ impl SegmentWriter {
 	// - the dictionary in an fst
 	// - the postings
 	// - the segment info
-	// The segment writer cannot be used after this.
+	// The segment writer cannot be used after this, which is
+	// enforced by the fact that "self" is moved.
 	pub fn finalize(mut self,) -> io::Result<()> {
 		let segment_info = self.segment_info();
 		self.postings_writer.close();
diff --git a/src/directory/directory.rs b/src/directory/directory.rs
index eca3692ec..1a73ce4ee 100644
--- a/src/directory/directory.rs
+++ b/src/directory/directory.rs
@@ -5,15 +5,6 @@ use std::fmt;
 use std::path::Path;
 use directory::{ReadOnlySource, WritePtr};
 
-///////////////////////////////////////////////////////////////
-//
-// #[derive(Debug)]
-// pub enum CreateError {
-//     RootDirectoryDoesNotExist,
-//     DirectoryAlreadyExists,
-//     CannotCreateTempDirectory(io::Error),
-// }
-
 pub trait Directory: fmt::Debug + Send + Sync {
 fn open_read(&self, path: &Path) -> io::Result<ReadOnlySource>;
     fn open_write(&mut self, path: &Path) -> io::Result<WritePtr>;