diff --git a/packages/zlib/zlib.pp b/packages/zlib/zlib.pp
index 1c005c89b9..75443c44f1 100644
--- a/packages/zlib/zlib.pp
+++ b/packages/zlib/zlib.pp
@@ -18,6 +18,7 @@ type
   Ulongf  = Longint;
   Pulongf = ^Ulongf;
   z_off_t = longint;
+  pbyte   = ^byte;
   pbytef  = ^byte;
 
   TAllocfunc = function (opaque:pointer; items:uInt; size:uInt):pointer;cdecl;
@@ -98,7 +99,7 @@ function inflateReset(var strm:TZStream):longint;cdecl;external libz name 'infla
 function compress(dest:pbytef;destLen:uLongf; source : pbytef; sourceLen:uLong):longint;cdecl;external libz name 'compress';
 function compress2(dest:pbytef;destLen:uLongf; source : pbytef; sourceLen:uLong; level:longint):longint;cdecl;external libz name 'compress2';
 function uncompress(dest:pbytef;destLen:uLongf; source : pbytef; sourceLen:uLong):longint;cdecl;external libz name 'uncompress';
-function gzopen(path:pbytef; mode:pbytef):gzFile;cdecl;external libz name 'gzopen';
+function gzopen(path:pchar; mode:pbytef):gzFile;cdecl;external libz name 'gzopen';
 function gzdopen(fd:longint; mode:pbytef):gzFile;cdecl;external libz name 'gzdopen';
 function gzsetparams(thefile:gzFile; level:longint; strategy:longint):longint;cdecl;external libz name 'gzsetparams';
 function gzread(thefile:gzFile; buf:pointer; len:cardinal):longint;cdecl;external libz name 'gzread';