diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h
index e643e69128..0ec0b4698e 100644
--- a/xen/include/xen/compiler.h
+++ b/xen/include/xen/compiler.h
@@ -33,6 +33,22 @@
 #define unreachable() __builtin_unreachable()
 #endif
 
+/*
+ * Add the pseudo keyword 'fallthrough' so case statement blocks
+ * must end with any of these keywords:
+ *   break;
+ *   fallthrough;
+ *   goto <label>;
+ *   return [expression];
+ *
+ *  gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes
+ */
+#if (!defined(__clang__) && (__GNUC__ >= 7))
+# define fallthrough        __attribute__((__fallthrough__))
+#else
+# define fallthrough        do {} while (0)  /* fallthrough */
+#endif
+
 #ifdef __clang__
 /* Clang can replace some vars with new automatic ones that go in .data;
  * mark all explicit-segment vars 'used' to prevent that. */