diff --git a/lib/libc/include/sys/cdefs.h b/lib/libc/include/sys/cdefs.h
index 5f794618..e30c1ff7 100644
--- a/lib/libc/include/sys/cdefs.h
+++ b/lib/libc/include/sys/cdefs.h
@@ -56,25 +56,6 @@
 #define __BEGIN_DECLS __BEGIN_CDECLS
 #define __END_DECLS __END_CDECLS
 
-/*
- * Testing against Clang-specific extensions.
- */
-#ifndef __has_attribute
-#define __has_attribute(x)  0
-#endif
-#ifndef __has_extension
-#define __has_extension     __has_feature
-#endif
-#ifndef __has_feature
-#define __has_feature(x)    0
-#endif
-#ifndef __has_include
-#define __has_include(x)    0
-#endif
-#ifndef __has_builtin
-#define __has_builtin(x)    0
-#endif
-
 /*-
  * Deal with _ANSI_SOURCE:
  * If it is defined, and no other compilation environment is explicitly
diff --git a/top/include/lk/compiler.h b/top/include/lk/compiler.h
index 04236826..d00104b0 100644
--- a/top/include/lk/compiler.h
+++ b/top/include/lk/compiler.h
@@ -138,11 +138,26 @@
 #define __FALLTHROUGH do {} while (0)
 #endif
 
+#ifndef __has_attribute
+#define __has_attribute(x)  0
+#endif
+#ifndef __has_extension
+#define __has_extension     __has_feature
+#endif
+#ifndef __has_feature
+#define __has_feature(x)    0
+#endif
+#ifndef __has_include
+#define __has_include(x)    0
+#endif
+#ifndef __has_builtin
+#define __has_builtin(x)    0
+#endif
+
 #ifndef __clang__
 #define __LEAF_FN __attribute__((__leaf__))
 #define __OPTIMIZE(x) __attribute__((optimize(x)))
 #define __THREAD_ANNOTATION(x)
-#define __has_feature(x) 0
 #else
 #define __LEAF_FN
 #define __OPTIMIZE(x)