diff --git a/lib/zlib/zutil.h b/lib/zlib/zutil.h
index b079ea6..0bc7f4e 100644
--- a/lib/zlib/zutil.h
+++ b/lib/zlib/zutil.h
@@ -1,5 +1,5 @@
 /* zutil.h -- internal interface and configuration of the compression library
- * Copyright (C) 1995-2016 Jean-loup Gailly, Mark Adler
+ * Copyright (C) 1995-2022 Jean-loup Gailly, Mark Adler
  * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
@@ -29,10 +29,6 @@
 #  include <stdlib.h>
 #endif
 
-#ifdef Z_SOLO
-   typedef long ptrdiff_t;  /* guess -- will be caught if guess is wrong */
-#endif
-
 #ifndef local
 #  define local static
 #endif
@@ -46,6 +42,17 @@
 typedef ush FAR ushf;
 typedef unsigned long  ulg;
 
+#if !defined(Z_U8) && !defined(Z_SOLO) && defined(STDC)
+#  include <limits.h>
+#  if (ULONG_MAX == 0xffffffffffffffff)
+#    define Z_U8 unsigned long
+#  elif (ULLONG_MAX == 0xffffffffffffffff)
+#    define Z_U8 unsigned long long
+#  elif (UINT_MAX == 0xffffffffffffffff)
+#    define Z_U8 unsigned
+#  endif
+#endif
+
 extern z_const char * const z_errmsg[10]; /* indexed by 2-zlib_error */
 /* (size given to avoid silly warnings with Visual C++) */
 
@@ -170,10 +177,6 @@
 #if (defined(_MSC_VER) && (_MSC_VER > 600)) && !defined __INTERIX
 #  if defined(_WIN32_WCE)
 #    define fdopen(fd,mode) NULL /* No fdopen() */
-#    ifndef _PTRDIFF_T_DEFINED
-       typedef int ptrdiff_t;
-#      define _PTRDIFF_T_DEFINED
-#    endif
 #  else
 #    define fdopen(fd,type)  _fdopen(fd,type)
 #  endif
@@ -190,6 +193,7 @@
     (!defined(_LARGEFILE64_SOURCE) || _LFS64_LARGEFILE-0 == 0)
     ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
     ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
+    ZEXTERN uLong ZEXPORT crc32_combine_gen64 OF((z_off_t));
 #endif
 
         /* common defaults */