diff --git a/boards/px4/fmu-v6xrt/firmware.prototype b/boards/px4/fmu-v6xrt/firmware.prototype
index beccbcebbd..a94d419a3d 100644
--- a/boards/px4/fmu-v6xrt/firmware.prototype
+++ b/boards/px4/fmu-v6xrt/firmware.prototype
@@ -7,7 +7,7 @@
     "summary": "PX4FMUv6XRT",
     "version": "0.1",
     "image_size": 0,
-    "image_maxsize": 7340032,
+    "image_maxsize": 4063232,
     "git_identity": "",
     "board_revision": 0
 }