diff --git a/src/modules/navigator/navigation.h b/src/modules/navigator/navigation.h
index 439bbc02e3..69c0384b45 100644
--- a/src/modules/navigator/navigation.h
+++ b/src/modules/navigator/navigation.h
@@ -47,8 +47,10 @@
 
 #if defined(MEMORY_CONSTRAINED_SYSTEM)
 #  define NUM_MISSIONS_SUPPORTED 50
+#elif defined(__PX4_POSIX)
+#  define NUM_MISSIONS_SUPPORTED (UINT16_MAX-1) // This is allocated as needed.
 #else
-#  define NUM_MISSIONS_SUPPORTED 256
+#  define NUM_MISSIONS_SUPPORTED 2000 // This allocates a file of around 181 kB on the SD card.
 #endif
 
 #define NAV_EPSILON_POSITION	0.001f	/**< Anything smaller than this is considered zero */