Index: /trunk/src/libs/zlib-1.2.6/gzguts.h
===================================================================
--- /trunk/src/libs/zlib-1.2.6/gzguts.h	(revision 48285)
+++ /trunk/src/libs/zlib-1.2.6/gzguts.h	(revision 48286)
@@ -30,4 +30,10 @@
 #ifdef __TURBOC__
 #  include <io.h>
+#endif
+
+#ifdef VBOX /* Solves missing seek, read, open, close, write functions. */
+#  ifdef _MSC_VER
+#    include <io.h>
+#  endif
 #endif