diff --git a/libraries/AP_HAL/board/sitl.h b/libraries/AP_HAL/board/sitl.h
index 6b4b941151..71872427f8 100644
--- a/libraries/AP_HAL/board/sitl.h
+++ b/libraries/AP_HAL/board/sitl.h
@@ -5,7 +5,11 @@
 #define HAL_MEM_CLASS HAL_MEM_CLASS_1000
 #define HAL_OS_POSIX_IO 1
 #define HAL_OS_SOCKETS 1
+#if defined(STORAGE_USE_FLASH) && STORAGE_USE_FLASH==1
+#define HAL_STORAGE_SIZE            15360
+#else
 #define HAL_STORAGE_SIZE            16384
+#endif
 #define HAL_STORAGE_SIZE_AVAILABLE  HAL_STORAGE_SIZE
 #define HAL_BOARD_LOG_DIRECTORY "logs"
 #define HAL_BOARD_TERRAIN_DIRECTORY "terrain"