diff --git a/sys/sys/param.h b/sys/sys/param.h
index 8920f78..7fad5d7 100644
--- a/sys/sys/param.h
+++ b/sys/sys/param.h
@@ -344,4 +344,11 @@ __END_DECLS
  */
 #define __PAST_END(array, offset) (((__typeof__(*(array)) *)(array))[offset])
 
+/*
+ * Make sure to read given variable only once. Useful e.g. if you are reading
+ * a pointer and dereference it multiple times, but some other code may set it
+ * to something else.
+ */
+#define READ_ONCE(var)  (*(volatile __typeof(var) *)&(var))
+
 #endif	/* _SYS_PARAM_H_ */