--- a/src/j2k_transcode.cc	2022-05-17 10:07:44.525679224 +0200
+++ b/src/j2k_transcode.cc	2022-05-17 10:04:18.846330309 +0200
@@ -46,7 +46,7 @@
 #include <openjpeg.h>
 #include <cmath>
 #include <iostream>
-
+#include <string>
 
 using std::min;
 using std::pow;
@@ -315,10 +315,13 @@
 	parameters.max_comp_size = parameters.max_cs_size / 1.25;
 	parameters.tcp_numlayers = 1;
 	parameters.tcp_mct = 1;
-	parameters.numgbits = fourk ? 2 : 1;
+	string numgbits = "GUARD_BITS=";
+	numgbits.append(std::to_string(fourk ? 2 : 1));
+	const char* extraopt[] { numgbits.data(), nullptr };
 
 	/* Setup the encoder parameters using the current image and user parameters */
 	opj_setup_encoder (encoder, &parameters, xyz->opj_image());
+	opj_encoder_set_extra_options(encoder, extraopt);
 
 	auto stream = opj_stream_default_create (OPJ_FALSE);
 	if (!stream) {