diff --git a/sys/sys/_types.h b/sys/sys/_types.h
--- a/sys/sys/_types.h
+++ b/sys/sys/_types.h
@@ -161,10 +161,7 @@
 typedef int		__cpusetid_t;	/* cpuset identifier. */
 typedef __int64_t	__daddr_t;	/* bwrite(3), FIOBMAP2, etc */
 
-#ifndef __has_feature
-#define __has_feature(x)        0
-#endif
-#if !__has_feature(capabilities)
+#ifndef __SIZEOF_INTCAP__
 /*
  * On non-CHERI systems, define __(u)intcap_t to __(u)intptr_t so that
  * hybrid-C code which needs to be explicitly aware of capabilities can