diff -upk.orig zlib-1.2.3.orig/gzio.c zlib-1.2.3/gzio.c
--- zlib-1.2.3.orig/gzio.c	2005-07-02 15:48:46 +0000
+++ zlib-1.2.3/gzio.c	2005-07-01 15:25:35 +0000
@@ -398,20 +398,17 @@ int ZEXPORT gzread (file, buf, len)
 {
     gz_stream *s = (gz_stream*)file;
     Bytef *start = (Bytef*)buf; /* starting point for crc computation */
-    Byte  *next_out; /* == stream.next_out but not forced far (for MSDOS) */
 
     if (s == NULL || s->mode != 'r') return Z_STREAM_ERROR;
 
     if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) return -1;
     if (s->z_err == Z_STREAM_END) return 0;  /* EOF */
 
-    next_out = (Byte*)buf;
     s->stream.next_out = (Bytef*)buf;
     s->stream.avail_out = len;
 
     if (s->stream.avail_out && s->back != EOF) {
-        *next_out++ = s->back;
-        s->stream.next_out++;
+        *s->stream.next_out++ = s->back;
         s->stream.avail_out--;
         s->back = EOF;
         s->out++;
@@ -430,15 +427,14 @@ int ZEXPORT gzread (file, buf, len)
             if (n > s->stream.avail_out) n = s->stream.avail_out;
             if (n > 0) {
                 zmemcpy(s->stream.next_out, s->stream.next_in, n);
-                next_out += n;
-                s->stream.next_out = next_out;
+                s->stream.next_out += n;
                 s->stream.next_in   += n;
                 s->stream.avail_out -= n;
                 s->stream.avail_in  -= n;
             }
             if (s->stream.avail_out > 0) {
                 s->stream.avail_out -=
-                    (uInt)fread(next_out, 1, s->stream.avail_out, s->file);
+                    (uInt)fread(s->stream.next_out, 1, s->stream.avail_out, s->file);
             }
             len -= s->stream.avail_out;
             s->in  += len;