--- a/zlib.h	2010-01-18 18:01:57.000000000 +0200
+++ b/zlib.h	2010-01-18 18:01:02.000000000 +0200
@@ -1187,10 +1187,13 @@
 
      The next call of gzclose on the returned gzFile will also close the file
    descriptor fd, just like fclose(fdopen(fd), mode) closes the file descriptor
-   fd.  If you want to keep fd open, use gzdopen(dup(fd), mode).
+   fd.  If you want to keep fd open, use gzdopen(dupfd=dup(fd), mode).
 
      gzdopen returns NULL if there was insufficient memory to allocate the
-   (de)compression state.
+   (de)compression state, an invalid mode was specified, there was a zlib 
+   version mismatch, or if fdopen fails. In either of these cases it is the 
+   responsibility of the caller to close the file descriptor, since gzdopen
+   leaves it open, and gzclose can't close it.
 */
 
 ZEXTERN int ZEXPORT gzbuffer OF((gzFile file, unsigned size));