diff --git a/include/haproxy/arg-t.h b/include/haproxy/arg-t.h
index 3c5591f28..cb94ef7ea 100644
--- a/include/haproxy/arg-t.h
+++ b/include/haproxy/arg-t.h
@@ -82,6 +82,7 @@ enum {
 	ARGC_UBK,      /* use_backend message */
 	ARGC_USRV,     /* use-server message */
 	ARGC_HERR,     /* http-error */
+	ARGC_OT,       /* opentracing scope args */
 };
 
 /* flags used when compiling and executing regex */
diff --git a/src/log.c b/src/log.c
index 1fb98c13b..59d68a93c 100644
--- a/src/log.c
+++ b/src/log.c
@@ -284,6 +284,8 @@ static inline const char *fmt_directive(const struct proxy *curproxy)
 		return "use_backend";
 	case ARGC_HERR:
 		return "http-error";
+	case ARGC_OT:
+		return "ot-scope";
 	default:
 		return "undefined(please report this bug)"; /* must never happen */
 	}
diff --git a/src/sample.c b/src/sample.c
index a9663bbfb..abf820bc7 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -1136,6 +1136,7 @@ int smp_resolve_args(struct proxy *p)
 		case ARGC_SRV:   where = "in server directive in"; break;
 		case ARGC_SPOE:  where = "in spoe-message directive in"; break;
 		case ARGC_HERR:  where = "in http-error directive in"; break;
+		case ARGC_OT:    where = "in ot-scope directive in"; break;
 		}
 
 		/* set a few default settings */