diff --git a/src/log.c b/src/log.c
index 369dc34b1..f1fe40c82 100644
--- a/src/log.c
+++ b/src/log.c
@@ -1488,8 +1488,10 @@ int build_logline(struct session *s, char *dst, size_t maxsize, struct list *lis
 				break;
 
 			case LOG_FMT_UNIQUEID: // %ID
+				ret = NULL;
 				src = s->unique_id;
-				ret = lf_text(tmplog, src, maxsize - (tmplog - dst), tmp);
+				if (src)
+					ret = lf_text(tmplog, src, maxsize - (tmplog - dst), tmp);
 				if (ret == NULL)
 					goto out;
 				tmplog = ret;
@@ -1541,6 +1543,12 @@ void sess_log(struct session *s)
 			level = LOG_ERR;
 	}
 
+	/* if unique-id was not generated */
+	if (!s->unique_id && !LIST_ISEMPTY(&s->fe->format_unique_id)) {
+		if ((s->unique_id = pool_alloc2(pool2_uniqueid)) != NULL)
+			build_logline(s, s->unique_id, UNIQUEID_LEN, &s->fe->format_unique_id);
+	}
+
 	tmplog = update_log_hdr();
 	size = tmplog - logline;
 	size += build_logline(s, tmplog, sizeof(logline) - size, &s->fe->logformat);
diff --git a/src/proto_http.c b/src/proto_http.c
index 8d6eaf519..6ab2676f6 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -2635,9 +2635,6 @@ int http_wait_for_request(struct session *s, struct channel *req, int an_bit)
 		}
 	}
 
-	if (!LIST_ISEMPTY(&s->fe->format_unique_id))
-		s->unique_id = pool_alloc2(pool2_uniqueid);
-
 	/* 4. We may have to convert HTTP/0.9 requests to HTTP/1.0 */
 	if (unlikely(msg->sl.rq.v_l == 0) && !http_upgrade_v09_to_v10(txn))
 		goto return_bad_req;
@@ -3950,8 +3947,12 @@ int http_process_request(struct session *s, struct channel *req, int an_bit)
 
 	/* add unique-id if "header-unique-id" is specified */
 
-	if (!LIST_ISEMPTY(&s->fe->format_unique_id))
+	if (!LIST_ISEMPTY(&s->fe->format_unique_id)) {
+		if ((s->unique_id = pool_alloc2(pool2_uniqueid)) == NULL)
+			goto return_bad_req;
+		s->unique_id[0] = '\0';
 		build_logline(s, s->unique_id, UNIQUEID_LEN, &s->fe->format_unique_id);
+	}
 
 	if (s->fe->header_unique_id && s->unique_id) {
 		chunk_printf(&trash, "%s: %s", s->fe->header_unique_id, s->unique_id);