diff --git a/include/types/proxy.h b/include/types/proxy.h
index b1b90e8..7664618 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -117,6 +117,7 @@
 #define PR_O2_RSPBUG_OK	0x00000010      /* let buggy responses pass through */
 #define PR_O2_NOLOGNORM	0x00000020      /* don't log normal traffic, only errors and retries */
 #define PR_O2_LOGERRORS	0x00000040      /* log errors and retries at level LOG_ERR */
+#define PR_O2_SMARTACC 	0x00000080      /* don't immediately ACK request after accept */
 
 /* This structure is used to apply fast weighted round robin on a server group */
 struct fwrr_group {