diff --git a/include/types/session.h b/include/types/session.h
index 7fde0aa..6054924 100644
--- a/include/types/session.h
+++ b/include/types/session.h
@@ -65,9 +65,9 @@
 #define SN_ERR_PRXCOND	0x00005000	/* the proxy decided to close (deny...) */
 #define SN_ERR_RESOURCE	0x00006000	/* the proxy encountered a lack of a local resources (fd, mem, ...) */
 #define SN_ERR_INTERNAL	0x00007000	/* the proxy encountered an internal error */
-#define SN_ERR_MASK	0x00007000	/* mask to get only session error flags */
+#define SN_ERR_DOWN	0x00008000	/* the proxy killed a session because the backend became unavailable */
+#define SN_ERR_MASK	0x0000f000	/* mask to get only session error flags */
 #define SN_ERR_SHIFT	12		/* bit shift */
-#define SN_BE_TRACK_SC1 0x00008000	/* backend tracks stick-counter 1 */
 
 /* session state at termination, bits values 0x10000 to 0x70000 (0-7 shift 16) */
 #define SN_FINST_R	0x00010000	/* session ended during client request */
@@ -79,9 +79,10 @@
 #define SN_FINST_T	0x00070000	/* session ended tarpitted */
 #define SN_FINST_MASK	0x00070000	/* mask to get only final session state flags */
 #define	SN_FINST_SHIFT	16		/* bit shift */
-#define SN_BE_TRACK_SC2 0x00080000	/* backend tracks stick-counter 2 */
 
-#define SN_IGNORE_PRST	0x00100000	/* ignore persistence */
+#define SN_IGNORE_PRST	0x00080000	/* ignore persistence */
+#define SN_BE_TRACK_SC1 0x00100000	/* backend tracks stick-counter 1 */
+#define SN_BE_TRACK_SC2 0x00200000	/* backend tracks stick-counter 2 */
 
 /* Termination sequence tracing.
  *