diff --git a/src/core/writer.rs b/src/core/writer.rs
index 6b269c4bc..d56f1a55e 100644
--- a/src/core/writer.rs
+++ b/src/core/writer.rs
@@ -18,7 +18,6 @@ pub struct IndexWriter {
 	schema: Schema,
 }
 
-
 impl IndexWriter {
 
     pub fn open(directory: &Index) -> io::Result<IndexWriter> {
@@ -32,8 +31,8 @@ impl IndexWriter {
 		})
     }
 
-    pub fn add(&mut self, doc: Document) -> io::Result<()> {
-        Rc::get_mut(&mut self.segment_writer).unwrap().add(doc, &self.schema)
+    pub fn add(&mut self, doc: &Document) -> io::Result<()> {
+        Rc::get_mut(&mut self.segment_writer).unwrap().add(&doc, &self.schema)
     }
 
     pub fn commit(&mut self,) -> io::Result<Segment> {
@@ -83,10 +82,6 @@ impl SegmentWriter {
 		self.segment_serializer.close()
 	}
 
-	pub fn max_doc(&self,) -> DocId {
-		self.max_doc
-	}
-
 	pub fn segment(&self,) -> Segment {
 		self.segment_serializer.segment()
 	}
@@ -102,7 +97,7 @@ impl SegmentWriter {
 		})
 	}
 
-    pub fn add(&mut self, doc: Document, schema: &Schema) -> io::Result<()> {
+    pub fn add(&mut self, doc: &Document, schema: &Schema) -> io::Result<()> {
         let doc_id = self.max_doc;
         for field_value in doc.text_fields() {
 			let field_options = schema.text_field_options(&field_value.field);
diff --git a/src/lib.rs b/src/lib.rs
index da95c3798..991c65ebb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -86,17 +86,17 @@ mod tests {
             {
                 let mut doc = Document::new();
                 doc.set(&text_field, "af b");
-                index_writer.add(doc).unwrap();
+                index_writer.add(&doc).unwrap();
             }
             {
                 let mut doc = Document::new();
                 doc.set(&text_field, "a b c");
-                index_writer.add(doc).unwrap();
+                index_writer.add(&doc).unwrap();
             }
             {
                 let mut doc = Document::new();
                 doc.set(&text_field, "a b c d");
-                index_writer.add(doc).unwrap();
+                index_writer.add(&doc).unwrap();
             }
 
             let commit_result = index_writer.commit();
@@ -123,17 +123,17 @@ mod tests {
             {
                 let mut doc = Document::new();
                 doc.set(&text_field, "af b");
-                index_writer.add(doc).unwrap();
+                index_writer.add(&doc).unwrap();
             }
             {
                 let mut doc = Document::new();
                 doc.set(&text_field, "a b c");
-                index_writer.add(doc).unwrap();
+                index_writer.add(&doc).unwrap();
             }
             {
                 let mut doc = Document::new();
                 doc.set(&text_field, "a b c d");
-                index_writer.add(doc).unwrap();
+                index_writer.add(&doc).unwrap();
             }
             let commit_result = index_writer.commit();
             commit_result.unwrap();