diff --git a/src/lib/openjp2/j2k.h b/src/lib/openjp2/j2k.h
index 4366fc43..7353071c 100644
--- a/src/lib/openjp2/j2k.h
+++ b/src/lib/openjp2/j2k.h
@@ -1024,7 +1024,7 @@ opj_bool opj_j2k_encode_v2(	opj_j2k_v2_t * p_j2k,
  *
  * @return true if the codec is valid.
  */
-opj_bool OPJ_CALLCONV opj_j2k_start_compress(opj_j2k_v2_t *p_j2k,
+OPJ_API opj_bool OPJ_CALLCONV opj_j2k_start_compress(opj_j2k_v2_t *p_j2k,
 							    opj_stream_private_t *p_stream,
 							    opj_image_t * p_image,
 							    opj_event_mgr_t * p_manager);