Index: sys/compat/linuxkpi/common/include/linux/kernel.h
===================================================================
--- sys/compat/linuxkpi/common/include/linux/kernel.h
+++ sys/compat/linuxkpi/common/include/linux/kernel.h
@@ -700,7 +700,7 @@
 }
 
 #define	DECLARE_FLEX_ARRAY(_t, _n)					\
-    struct { struct { } __dummy_ ## _n; _t _n[]; }
+    struct { struct { } __dummy_ ## _n; _t _n[0]; }
 
 /*
  * Checking if an option is defined would be easy if we could do CPP inside CPP.