diff --git a/lib/zlib/deflate.js b/lib/zlib/deflate.js
index d9bec99..7e0754f 100644
--- a/lib/zlib/deflate.js
+++ b/lib/zlib/deflate.js
@@ -132,16 +132,16 @@ function read_buf(strm, buf, start, size) {
  *    option -- not supported here).
  */
 function fill_window(s) {
-  var wsize = s.w_size;
-  var p = 0, n = 0, m = 0;
+  var _w_size = s.w_size;
+  var p = 0, n = 0, m = 0, more, str;
 
   //Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
 
   do {
-    var more = s.window_size - s.lookahead - s.strstart;
+    more = s.window_size - s.lookahead - s.strstart;
 
     if (more === 0 && s.strstart === 0 && s.lookahead === 0) {
-      more = wsize;
+      more = _w_size;
 
     } else if (more === -1) {
       /* Very unlikely, but possible on 16 bit machine if
@@ -154,13 +154,13 @@ function fill_window(s) {
     /* If the window is almost full and there is insufficient lookahead,
      * move the upper half to the lower one to make room in the upper half.
      */
-    if (s.strstart >= wsize + (wsize - MIN_LOOKAHEAD)) {
+    if (s.strstart >= _w_size + (_w_size - MIN_LOOKAHEAD)) {
 
-      utils.arraySet(s.window, s.window, wsize, wsize, 0);
-      s.match_start -= wsize;
-      s.strstart -= wsize;
+      utils.arraySet(s.window, s.window, _w_size, _w_size, 0);
+      s.match_start -= _w_size;
+      s.strstart -= _w_size;
       /* we now have strstart >= MAX_DIST */
-      s.block_start -= wsize;
+      s.block_start -= _w_size;
 
       /* Slide the hash table (could be avoided with 32 bit values
        at the expense of memory usage). We slide even when level == 0
@@ -172,20 +172,20 @@ function fill_window(s) {
       p = n;
       do {
         m = s.head[--p];
-        s.head[p] = m >= wsize ? m - wsize : 0;
+        s.head[p] = m >= _w_size ? m - _w_size : 0;
       } while (--n);
 
-      n = wsize;
+      n = _w_size;
       p = n;
       do {
-        m = s.head[--p];
-        s.head[p] = m >= wsize ? m - wsize : 0;
+        m = s.prev[--p];
+        s.prev[p] = m >= _w_size ? m - _w_size : 0;
         /* If n is not on any hash chain, prev[n] is garbage but
          * its value will never be used.
          */
       } while (--n);
 
-      more += wsize;
+      more += _w_size;
     }
     if (s.strm.avail_in === 0) {
       break;
@@ -208,7 +208,7 @@ function fill_window(s) {
 
     /* Initialize the hash value now that we have some input: */
     if (s.lookahead + s.insert >= MIN_MATCH) {
-      var str = s.strstart - s.insert;
+      str = s.strstart - s.insert;
       s.ins_h = s.window[str];
       s.ins_h = update_hash(s, s.ins_h, s.window[str + 1]);
 //#if MIN_MATCH != 3