diff --git a/include/kerncompat.h b/include/kerncompat.h
index 31cd9d8d..eb98afbb 100644
--- a/include/kerncompat.h
+++ b/include/kerncompat.h
@@ -305,6 +305,9 @@ static inline void up_read(struct rw_semaphore *sem)
 #if defined __has_attribute
 # if __has_attribute(__fallthrough__)
 #  define fallthrough			__attribute__((__fallthrough__))
+# else
+/* Compatibility with gcc 5.x and 6.x that don't have the attribute. */
+#  define fallthrough			do {} while (0)  /* fallthrough */
 # endif
 #else
 # define fallthrough			do {} while (0)  /* fallthrough */