diff --git a/MdePkg/Include/Base.h b/MdePkg/Include/Base.h
index e02970a..7caebbe 100644
--- a/MdePkg/Include/Base.h
+++ b/MdePkg/Include/Base.h
@@ -59,7 +59,7 @@
 /// up to the compiler to remove any code past that point.
 ///
 #define UNREACHABLE()  __builtin_unreachable ()
-  #elif defined (__has_feature)
+  #elif defined (__has_builtin) && defined (__has_feature)
     #if __has_builtin (__builtin_unreachable)
 ///
 /// Signal compilers and analyzers that this call is not reachable.  It is