diff --git a/include/common/tools.h b/include/common/tools.h
index 398383a..9610601 100644
--- a/include/common/tools.h
+++ b/include/common/tools.h
@@ -33,6 +33,8 @@
 #define MAX(a, b) (((a) > (b)) ? (a) : (b))
 #endif
 
+#define SWAP(a, b) do { typeof(a) t; t = a; a = b; b = t; } while(0)
+
 /* return an integer of type <ret> with only the highest bit set. <ret> may be
  * both a variable or a type.
  */