diff --git a/.gitignore b/.gitignore
index 4a4a9c099..d9544bcb9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@ target
 target/debug
 target/release
 Cargo.lock
+.DS_Store
diff --git a/src/postings/recorder.rs b/src/postings/recorder.rs
index 8573180e7..e90d31ae1 100644
--- a/src/postings/recorder.rs
+++ b/src/postings/recorder.rs
@@ -18,13 +18,13 @@ impl Recorder for NothingRecorder {
         NothingRecorder
     }
     
-    fn record_position(&mut self, position: u32) {
+    fn record_position(&mut self, _position: u32) {
     }
     
     fn close_doc(&mut self,) {
     }
     
-    fn get_tf_and_posdeltas(&self, i: usize) -> (u32, &[u32]) {
+    fn get_tf_and_posdeltas(&self, _: usize) -> (u32, &[u32]) {
         (0u32, &EMPTY_ARRAY)
     }
 }
@@ -43,7 +43,7 @@ impl Recorder for TermFrequencyRecorder {
         }
     }
     
-    fn record_position(&mut self, position: u32) {
+    fn record_position(&mut self, _position: u32) {
         self.current_tf += 1;
     }
     
diff --git a/src/postings/serializer.rs b/src/postings/serializer.rs
index ba7a86fae..70b483ce1 100644
--- a/src/postings/serializer.rs
+++ b/src/postings/serializer.rs
@@ -103,7 +103,7 @@ impl PostingsSerializer {
         if self.is_positions_enabled {
             self.position_deltas.extend_from_slice(position_deltas);
         }
-        if self.doc_ids.len() == 128 { 
+        if self.doc_ids.len() == NUM_DOCS_PER_BLOCK { 
             {
                 // encode the positions
                 let block_encoded: &[u32] = self.block_encoder.encode_sorted(&self.doc_ids);
diff --git a/src/postings/writer.rs b/src/postings/writer.rs
index d14e75bd7..1cb7701a2 100644
--- a/src/postings/writer.rs
+++ b/src/postings/writer.rs
@@ -47,11 +47,9 @@ impl<Rec: Recorder> TermPostingsWriter<Rec> {
     }
     
     pub fn serialize(&self, serializer: &mut PostingsSerializer) -> io::Result<()> {
-        let mut positions_idx = 0;
         for (i, doc) in self.doc_ids.iter().enumerate() {
             let (term_freq, position_deltas) = self.recorder.get_tf_and_posdeltas(i);
             try!(serializer.write_doc(doc.clone(), term_freq, position_deltas));
-            positions_idx += term_freq as usize;
         }
         Ok(())
     }