diff --git a/src/platforms/px4_defines.h b/src/platforms/px4_defines.h
index 25767c3881..797ee9a4c9 100644
--- a/src/platforms/px4_defines.h
+++ b/src/platforms/px4_defines.h
@@ -110,7 +110,7 @@ typedef param_t px4_param_t;
  * NuttX specific defines.
  ****************************************************************************/
 
-#define PX4_ROOTFSDIR
+#define PX4_ROOTFSDIR ""
 #define _PX4_IOC(x,y) _IOC(x,y)
 #define px4_statfs_buf_f_bavail_t int
 
@@ -174,7 +174,7 @@ using ::isfinite;
 
 // QURT specific
 #  include "dspal_math.h"
-#  define PX4_ROOTFSDIR
+#  define PX4_ROOTFSDIR ""
 #  define PX4_TICKS_PER_SEC 1000L
 #  define SIOCDEVPRIVATE 999999