diff --git a/client/fpga_compress.c b/client/fpga_compress.c
index 6af1846ef..a0ecbe485 100644
--- a/client/fpga_compress.c
+++ b/client/fpga_compress.c
@@ -113,6 +113,7 @@ int zlib_compress(FILE *infile[], uint8_t num_infiles, FILE *outfile)
 	compressed_fpga_stream.avail_in = i;
 	compressed_fpga_stream.zalloc = fpga_deflate_malloc;
 	compressed_fpga_stream.zfree = fpga_deflate_free;
+	compressed_fpga_stream.opaque = Z_NULL;
 	
 	ret = deflateInit2(&compressed_fpga_stream, 
 						COMPRESS_LEVEL,