$OpenBSD: patch-src_synfig_zstreambuf_cpp,v 1.1 2017/12/07 22:42:50 rsadowski Exp $
Base zlib don't provide z_const.
Index: src/synfig/zstreambuf.cpp
--- src/synfig/zstreambuf.cpp.orig
+++ src/synfig/zstreambuf.cpp
@@ -74,7 +74,7 @@ bool zstreambuf::pack(std::vector<char> &dest, const v
 	)) return false;
 
 	stream.avail_in = size;
-	stream.next_in = (z_const Bytef*)src;
+	stream.next_in = ( Bytef*)src;
 	bool result = true;
 	do
 	{
@@ -104,7 +104,7 @@ size_t zstreambuf::pack(void *dest, size_t dest_size, 
 	)) return 0;
 
 	stream.avail_in = src_size;
-	stream.next_in = (z_const Bytef*)src;
+	stream.next_in = ( Bytef*)src;
 	stream.avail_out = dest_size;
 	stream.next_out = (Bytef*)dest;
 	size_t size = 0;
@@ -120,7 +120,7 @@ bool zstreambuf::unpack(std::vector<char> &dest, const
 	if (Z_OK != inflateInit2(&stream, option_window_bits )) return false;
 
 	stream.avail_in = size;
-	stream.next_in = (z_const Bytef*)src;
+	stream.next_in = ( Bytef*)src;
 	bool result = true;
 	do
 	{
@@ -144,7 +144,7 @@ size_t zstreambuf::unpack(void *dest, size_t dest_size
 	if (Z_OK != inflateInit2(&stream, option_window_bits )) return 0;
 
 	stream.avail_in = src_size;
-	stream.next_in = (z_const Bytef*)src;
+	stream.next_in = ( Bytef*)src;
 	stream.avail_out = dest_size;
 	stream.next_out = (Bytef*)dest;
 	size_t size = 0;
