--- ioapi.c.orig	2014-05-24 09:54:26.298884453 +0200
+++ ioapi.c	2014-05-24 09:50:22.708762308 +0200
@@ -89,6 +89,8 @@
 static uLong   ZCALLBACK fwrite_file_func OF((voidpf opaque, voidpf stream, const void* buf,uLong size));
 static ZPOS64_T ZCALLBACK ftell64_file_func OF((voidpf opaque, voidpf stream));
 static long    ZCALLBACK fseek64_file_func OF((voidpf opaque, voidpf stream, ZPOS64_T offset, int origin));
+static int     ZCALLBACK fflush_file_func OF((voidpf opaque, voidpf stream));
+
 static int     ZCALLBACK fclose_file_func OF((voidpf opaque, voidpf stream));
 static int     ZCALLBACK ferror_file_func OF((voidpf opaque, voidpf stream));
 
@@ -206,6 +208,12 @@
     return ret;
 }
 
+static int ZCALLBACK fflush_file_func (voidpf opaque, voidpf stream)
+{
+    int ret;
+    ret = fflush((FILE *)stream);
+    return ret;
+}
 
 static int ZCALLBACK fclose_file_func (voidpf opaque, voidpf stream)
 {
@@ -229,6 +237,7 @@
     pzlib_filefunc_def->zwrite_file = fwrite_file_func;
     pzlib_filefunc_def->ztell_file = ftell_file_func;
     pzlib_filefunc_def->zseek_file = fseek_file_func;
+    pzlib_filefunc_def->zflush_file = fflush_file_func;
     pzlib_filefunc_def->zclose_file = fclose_file_func;
     pzlib_filefunc_def->zerror_file = ferror_file_func;
     pzlib_filefunc_def->opaque = NULL;