diff -up zlib-1.2.5.3/contrib/minizip/ioapi.c.zip64 zlib-1.2.5.3/contrib/minizip/ioapi.c
--- zlib-1.2.5.3/contrib/minizip/ioapi.c.zip64	2010-07-18 18:04:24.000000000 +0200
+++ zlib-1.2.5.3/contrib/minizip/ioapi.c	2012-01-16 20:40:41.347441358 +0100
@@ -59,7 +59,7 @@ ZPOS64_T call_ztell64 (const zlib_filefu
     else
     {
         uLong tell_uLong = (*(pfilefunc->ztell32_file))(pfilefunc->zfile_func64.opaque,filestream);
-        if ((tell_uLong) == ((uLong)-1))
+        if ((tell_uLong) == MAXU32)
             return (ZPOS64_T)-1;
         else
             return tell_uLong;
diff -up zlib-1.2.5.3/contrib/minizip/ioapi.h.zip64 zlib-1.2.5.3/contrib/minizip/ioapi.h
--- zlib-1.2.5.3/contrib/minizip/ioapi.h.zip64	2010-07-18 18:04:24.000000000 +0200
+++ zlib-1.2.5.3/contrib/minizip/ioapi.h	2012-01-16 20:40:41.348441218 +0100
@@ -86,6 +86,8 @@ typedef  64BIT_INT_CUSTOM_TYPE ZPOS64_T;
 typedef uint64_t ZPOS64_T;
 #else
 
+/* Maximum unsigned 32-bit value used as placeholder for zip64 */
+#define MAXU32 0xffffffff
 
 #if defined(_MSC_VER) || defined(__BORLANDC__)
 typedef unsigned __int64 ZPOS64_T;
diff -up zlib-1.2.5.3/contrib/minizip/unzip.c.zip64 zlib-1.2.5.3/contrib/minizip/unzip.c
--- zlib-1.2.5.3/contrib/minizip/unzip.c.zip64	2010-04-23 15:51:38.000000000 +0200
+++ zlib-1.2.5.3/contrib/minizip/unzip.c	2012-01-16 20:40:41.351440776 +0100
@@ -1040,26 +1040,26 @@ local int unz64local_GetCurrentFileInfoI
             {
                                                         uLong uL;
 
-                                                                if(file_info.uncompressed_size == (ZPOS64_T)(unsigned long)-1)
+                                                                if(file_info.uncompressed_size == MAXU32)
                                                                 {
                                                                         if (unz64local_getLong64(&s->z_filefunc, s->filestream,&file_info.uncompressed_size) != UNZ_OK)
                                                                                         err=UNZ_ERRNO;
                                                                 }
 
-                                                                if(file_info.compressed_size == (ZPOS64_T)(unsigned long)-1)
+                                                                if(file_info.compressed_size == MAXU32)
                                                                 {
                                                                         if (unz64local_getLong64(&s->z_filefunc, s->filestream,&file_info.compressed_size) != UNZ_OK)
                                                                                   err=UNZ_ERRNO;
                                                                 }
 
-                                                                if(file_info_internal.offset_curfile == (ZPOS64_T)(unsigned long)-1)
+                                                                if(file_info_internal.offset_curfile == MAXU32)
                                                                 {
                                                                         /* Relative Header offset */
                                                                         if (unz64local_getLong64(&s->z_filefunc, s->filestream,&file_info_internal.offset_curfile) != UNZ_OK)
                                                                                 err=UNZ_ERRNO;
                                                                 }
 
-                                                                if(file_info.disk_num_start == (unsigned long)-1)
+                                                                if(file_info.disk_num_start == MAXU32)
                                                                 {
                                                                         /* Disk Start Number */
                                                                         if (unz64local_getLong(&s->z_filefunc, s->filestream,&uL) != UNZ_OK)