diff --git a/src/modules/mavlink/CMakeLists.txt b/src/modules/mavlink/CMakeLists.txt
index 80df1227a4..d5b39ff374 100644
--- a/src/modules/mavlink/CMakeLists.txt
+++ b/src/modules/mavlink/CMakeLists.txt
@@ -39,6 +39,7 @@ px4_add_module(
 	COMPILE_FLAGS
 		-Wno-cast-align # TODO: fix and enable
 		-Wno-address-of-packed-member # TODO: fix in c_library_v2
+		#-DDEBUG_BUILD
 	INCLUDES
 		${PX4_SOURCE_DIR}/mavlink/include/mavlink
 	SRCS
diff --git a/src/modules/mavlink/mavlink_mission.cpp b/src/modules/mavlink/mavlink_mission.cpp
index 23c83f615b..d8a95d9397 100644
--- a/src/modules/mavlink/mavlink_mission.cpp
+++ b/src/modules/mavlink/mavlink_mission.cpp
@@ -273,7 +273,7 @@ MavlinkMissionManager::send_mission_current(int32_t seq)
 		/* don't broadcast if no WPs */
 
 	} else {
-		PX4_DEBUG("WPM: Send MISSION_CURRENT ERROR: seq %u out of bounds", seq);
+		PX4_DEBUG("WPM: Send MISSION_CURRENT ERROR: seq %d out of bounds", seq);
 
 		_mavlink->send_statustext_critical("ERROR: wp index out of bounds");
 	}